diff --git a/src/NUnitEngine/nunit.engine.core.tests/Drivers/NUnitFrameworkDriverTests.cs b/src/NUnitEngine/nunit.engine.core.tests/Drivers/NUnitFrameworkDriverTests.cs
index d317e9b4f..011c6b9c7 100644
--- a/src/NUnitEngine/nunit.engine.core.tests/Drivers/NUnitFrameworkDriverTests.cs
+++ b/src/NUnitEngine/nunit.engine.core.tests/Drivers/NUnitFrameworkDriverTests.cs
@@ -14,8 +14,8 @@ namespace NUnit.Engine.Drivers
     // Functional tests of the NUnitFrameworkDriver calling into the framework.
 #if NETFRAMEWORK
     [TestFixture("2009")]
-    [TestFixture("2018")]
 #endif
+    [TestFixture("2018")]
     public class NUnitFrameworkDriverTests
     {
         private const string MOCK_ASSEMBLY = "mock-assembly.dll";
@@ -26,13 +26,11 @@ public class NUnitFrameworkDriverTests
         private NUnitFrameworkDriver _driver;
         private string _mockAssemblyPath;
 
-#if NETFRAMEWORK
         private string _whichApi;
         public NUnitFrameworkDriverTests(string whichApi)
         {
             _whichApi = whichApi;
         }
-#endif
 
         [SetUp]
         public void CreateDriver()
@@ -125,6 +123,23 @@ public void RunTestsAction_WithoutLoad_ThrowsInvalidOperationException()
             Assert.That(ex.Message, Is.EqualTo(LOAD_MESSAGE));
         }
 
+        [Test]
+        public void RunTestsAction_WithInvalidFilterElement_ThrowsException()
+        {
+            _driver.Load(_mockAssemblyPath, _settings);
+
+            var invalidFilter = "<filter><invalidElement>foo</invalidElement></filter>";
+            var ex = Assert.Catch(() => _driver.Run(new NullListener(), invalidFilter));
+
+            if (_whichApi == "2018")
+            {
+                Assert.That(ex, Is.TypeOf<TargetInvocationException>());
+                Assert.That(ex.InnerException, Is.TypeOf<ArgumentException>());
+            }
+            else
+                Assert.That(ex, Is.TypeOf<NUnitEngineException>());
+        }
+
 #if NETFRAMEWORK
         // Nested Class tests Api Selection in the driver
         public class ApiSelectionTests()
@@ -146,23 +161,6 @@ public void CorrectApiIsSelected(string nunitVersion, string apiVersion)
             }
         }
 
-        [Test]
-        public void RunTestsAction_WithInvalidFilterElement_ThrowsException()
-        {
-            _driver.Load(_mockAssemblyPath, _settings);
-
-            var invalidFilter = "<filter><invalidElement>foo</invalidElement></filter>";
-            var ex = Assert.Catch(() => _driver.Run(new NullListener(), invalidFilter));
-
-            if (_whichApi == "2018")
-            {
-                Assert.That(ex, Is.TypeOf<TargetInvocationException>());
-                Assert.That(ex.InnerException, Is.TypeOf<ArgumentException>());
-            }
-            else
-                Assert.That(ex, Is.TypeOf<NUnitEngineException>());
-        }
-
         private class CallbackEventHandler : System.Web.UI.ICallbackEventHandler
         {
             private string? _result;
diff --git a/src/NUnitEngine/nunit.engine.core/Drivers/DriverService.cs b/src/NUnitEngine/nunit.engine.core/Drivers/DriverService.cs
index 48d33c8d3..802a2e5ff 100644
--- a/src/NUnitEngine/nunit.engine.core/Drivers/DriverService.cs
+++ b/src/NUnitEngine/nunit.engine.core/Drivers/DriverService.cs
@@ -70,7 +70,7 @@ public IFrameworkDriver GetDriver(AppDomain domain, TestPackage package, string
 
                 if (platform == "Silverlight" || platform == ".NETPortable" || platform == ".NETStandard" || platform == ".NETCompactFramework")
                     if (skipNonTestAssemblies)
-                        return new SkippedAssemblyFrameworkDriver(assemblyPath, "X");
+                        return new SkippedAssemblyFrameworkDriver(assemblyPath, package.ID);
                     else
                         return new InvalidAssemblyFrameworkDriver(assemblyPath, package.ID, platform + 
                             " test assemblies are not supported by this version of the engine");
diff --git a/src/NUnitEngine/nunit.engine.core/Drivers/NUnitFrameworkApi2009.cs b/src/NUnitEngine/nunit.engine.core/Drivers/NUnitFrameworkApi2009.cs
index 4fb9b40fa..acc022a58 100644
--- a/src/NUnitEngine/nunit.engine.core/Drivers/NUnitFrameworkApi2009.cs
+++ b/src/NUnitEngine/nunit.engine.core/Drivers/NUnitFrameworkApi2009.cs
@@ -64,15 +64,15 @@ public string Load(string testAssemblyPath, IDictionary<string, object> settings
 
                 try
                 {
-                _frameworkController = _testDomain.CreateInstanceAndUnwrap(
-                    _nunitRef.FullName,
-                    CONTROLLER_TYPE,
-                    false,
-                    0,
-                    null,
-                    new object[] { _testAssemblyPath, idPrefix, settings },
-                    null,
-                    null).ShouldNotBeNull();
+                    _frameworkController = _testDomain.CreateInstanceAndUnwrap(
+                        _nunitRef.FullName,
+                        CONTROLLER_TYPE,
+                        false,
+                        0,
+                        null,
+                        new object[] { _testAssemblyPath, idPrefix, settings },
+                        null,
+                        null).ShouldNotBeNull();
                 }
                 catch (BadImageFormatException ex) when (requestedRuntime != null)
                 {
@@ -152,10 +152,8 @@ private object CreateObject(string typeName, params object?[]? args)
             {
                 try
                 {
-                return _testDomain.CreateInstanceAndUnwrap(
-                    _nunitRef.FullName, typeName, false, 0, null, args, null, null)!;
-                //return _testDomain.CreateInstanceAndUnwrap(
-                //        _nunitRef.FullName, typeName, false, 0, null, args, null, null)!;
+                    return _testDomain.CreateInstanceAndUnwrap(
+                        _nunitRef.FullName, typeName, false, 0, null, args, null, null)!;
                 }
                 catch (TargetInvocationException ex)
                 {
diff --git a/src/NUnitEngine/nunit.engine.core/Drivers/NUnitFrameworkApi2018.cs b/src/NUnitEngine/nunit.engine.core/Drivers/NUnitFrameworkApi2018.cs
index 8d5778764..535388f19 100644
--- a/src/NUnitEngine/nunit.engine.core/Drivers/NUnitFrameworkApi2018.cs
+++ b/src/NUnitEngine/nunit.engine.core/Drivers/NUnitFrameworkApi2018.cs
@@ -40,7 +40,6 @@ public class NUnitFrameworkApi2018 : NUnitFrameworkApi
 
 #if NETCOREAPP
         private TestAssemblyLoadContext? _assemblyLoadContext;
-        //private Assembly? _testAssembly;
         private Assembly? _frameworkAssembly;
 #endif
 
@@ -63,7 +62,7 @@ public string Load(string testAssemblyPath, IDictionary<string, object> settings
             log.Info($"Loading {testAssemblyPath} - see separate log file");
 
             _testAssemblyPath = Path.GetFullPath(testAssemblyPath);
-            var idPrefix = string.IsNullOrEmpty(_driverId) ? "" : _driverId + "-";
+            var idPrefix = _driverId + "-";
 
 #if NETFRAMEWORK
             try
@@ -236,10 +235,10 @@ private object ExecuteMethod(MethodInfo? method, params object?[] args)
 #if NETFRAMEWORK
             return method.Invoke(_frameworkController, args).ShouldNotBeNull();
 #else
-            using (_assemblyLoadContext.ShouldNotBeNull().EnterContextualReflection())
-            {
-                return method.Invoke(_frameworkController, args).ShouldNotBeNull();
-            }
+            //using (_assemblyLoadContext.ShouldNotBeNull().EnterContextualReflection())
+            //{
+            return method.Invoke(_frameworkController, args).ShouldNotBeNull();
+            //}
 #endif
         }
 
diff --git a/src/NUnitEngine/nunit.engine.core/Drivers/NUnitFrameworkDriver.cs b/src/NUnitEngine/nunit.engine.core/Drivers/NUnitFrameworkDriver.cs
index 5c082e7cc..b876ba368 100644
--- a/src/NUnitEngine/nunit.engine.core/Drivers/NUnitFrameworkDriver.cs
+++ b/src/NUnitEngine/nunit.engine.core/Drivers/NUnitFrameworkDriver.cs
@@ -108,7 +108,7 @@ public NUnitFrameworkDriver(string id, AssemblyName nunitRef)
         /// An id prefix that will be passed to the test framework and used as part of the
         /// test ids created.
         /// </summary>
-        public string ID { get; } = string.Empty;
+        public string ID { get; }
 
         /// <summary>
         /// Loads the tests in an assembly.
diff --git a/src/NUnitEngine/nunit.engine.core/Runners/TestAgentRunner.cs b/src/NUnitEngine/nunit.engine.core/Runners/TestAgentRunner.cs
index 5f2fe6dfc..d71e58f14 100644
--- a/src/NUnitEngine/nunit.engine.core/Runners/TestAgentRunner.cs
+++ b/src/NUnitEngine/nunit.engine.core/Runners/TestAgentRunner.cs
@@ -136,8 +136,6 @@ public virtual void Unload() { }
         /// <returns>The count of test cases</returns>
         public int CountTestCases(TestFilter filter)
         {
-            GetLoadedDriver();
-
             try
             {
                 return GetLoadedDriver().CountTestCases(filter.Text);