diff --git a/src/systems/abstractsystem.jl b/src/systems/abstractsystem.jl
index efec8b7fd8..b6e2a79c3e 100644
--- a/src/systems/abstractsystem.jl
+++ b/src/systems/abstractsystem.jl
@@ -2914,7 +2914,7 @@ function Base.eltype(::Type{<:TreeIterator{ModelingToolkit.AbstractSystem}})
 end
 
 function check_array_equations_unknowns(eqs, dvs)
-    if any(eq -> Symbolics.isarraysymbolic(eq.lhs), eqs)
+    if any(eq -> eq isa Equation && Symbolics.isarraysymbolic(eq.lhs), eqs)
         throw(ArgumentError("The system has array equations. Call `structural_simplify` to handle such equations or scalarize them manually."))
     end
     if any(x -> Symbolics.isarraysymbolic(x), dvs)
diff --git a/src/systems/jumps/jumpsystem.jl b/src/systems/jumps/jumpsystem.jl
index 60b061b1da..a714d4b364 100644
--- a/src/systems/jumps/jumpsystem.jl
+++ b/src/systems/jumps/jumpsystem.jl
@@ -348,20 +348,8 @@ function DiffEqBase.DiscreteProblem(sys::JumpSystem, u0map, tspan::Union{Tuple,
     if !iscomplete(sys)
         error("A completed `JumpSystem` is required. Call `complete` or `structural_simplify` on the system before creating a `DiscreteProblem`")
     end
-    dvs = unknowns(sys)
-    ps = parameters(sys)
-
-    defs = defaults(sys)
-    defs = mergedefaults(defs, parammap, ps)
-    defs = mergedefaults(defs, u0map, dvs)
-
-    u0 = varmap_to_vars(u0map, dvs; defaults = defs, tofloat = false)
-    if has_index_cache(sys) && get_index_cache(sys) !== nothing
-        p = MTKParameters(sys, parammap, u0map)
-    else
-        p = varmap_to_vars(parammap, ps; defaults = defs, tofloat = false, use_union)
-    end
-
+    _, u0, p = process_SciMLProblem(EmptySciMLFunction, sys, u0map, parammap;
+        t = tspan === nothing ? nothing : tspan[1], use_union, tofloat = false, check_length = false)
     f = DiffEqBase.DISCRETE_INPLACE_DEFAULT
 
     observedfun = ObservedFunctionCache(sys; eval_expression, eval_module)
@@ -399,16 +387,9 @@ function DiscreteProblemExpr{iip}(sys::JumpSystem, u0map, tspan::Union{Tuple, No
     if !iscomplete(sys)
         error("A completed `JumpSystem` is required. Call `complete` or `structural_simplify` on the system before creating a `DiscreteProblemExpr`")
     end
-    dvs = unknowns(sys)
-    ps = parameters(sys)
-    defs = defaults(sys)
 
-    u0 = varmap_to_vars(u0map, dvs; defaults = defs, tofloat = false)
-    if has_index_cache(sys) && get_index_cache(sys) !== nothing
-        p = MTKParameters(sys, parammap, u0map)
-    else
-        p = varmap_to_vars(parammap, ps; defaults = defs, tofloat = false, use_union)
-    end
+    _, u0, p = process_SciMLProblem(EmptySciMLFunction, sys, u0map, parammap;
+        t = tspan === nothing ? nothing : tspan[1], use_union, tofloat = false, check_length = false)
     # identity function to make syms works
     quote
         f = DiffEqBase.DISCRETE_INPLACE_DEFAULT
@@ -454,19 +435,9 @@ function DiffEqBase.ODEProblem(sys::JumpSystem, u0map, tspan::Union{Tuple, Nothi
     if !iscomplete(sys)
         error("A completed `JumpSystem` is required. Call `complete` or `structural_simplify` on the system before creating a `DiscreteProblem`")
     end
-    dvs = unknowns(sys)
-    ps = parameters(sys)
-
-    defs = defaults(sys)
-    defs = mergedefaults(defs, parammap, ps)
-    defs = mergedefaults(defs, u0map, dvs)
 
-    u0 = varmap_to_vars(u0map, dvs; defaults = defs, tofloat = false)
-    if has_index_cache(sys) && get_index_cache(sys) !== nothing
-        p = MTKParameters(sys, parammap, u0map)
-    else
-        p = varmap_to_vars(parammap, ps; defaults = defs, tofloat = false, use_union)
-    end
+    _, u0, p = process_SciMLProblem(EmptySciMLFunction, sys, u0map, parammap;
+        t = tspan === nothing ? nothing : tspan[1], use_union, tofloat = false, check_length = false)
 
     observedfun = ObservedFunctionCache(sys; eval_expression, eval_module)
 
diff --git a/src/systems/problem_utils.jl b/src/systems/problem_utils.jl
index 2b894eb7ee..e530e62eed 100644
--- a/src/systems/problem_utils.jl
+++ b/src/systems/problem_utils.jl
@@ -332,6 +332,18 @@ function get_temporary_value(p)
     end
 end
 
+"""
+    $(TYPEDEF)
+
+A simple utility meant to be used as the `constructor` passed to `process_SciMLProblem` in
+case constructing a SciMLFunction is not required.
+"""
+struct EmptySciMLFunction end
+
+function EmptySciMLFunction(args...; kwargs...)
+    return nothing
+end
+
 """
     $(TYPEDSIGNATURES)
 
diff --git a/src/utils.jl b/src/utils.jl
index e8ed131d78..1e54e7047b 100644
--- a/src/utils.jl
+++ b/src/utils.jl
@@ -610,6 +610,15 @@ function collect_constants!(constants, expr::Symbolic)
     end
 end
 
+function collect_constants!(constants, expr::Union{ConstantRateJump, VariableRateJump})
+    collect_constants!(constants, expr.rate)
+    collect_constants!(constants, expr.affect!)
+end
+
+function collect_constants!(constants, ::MassActionJump)
+    return constants
+end
+
 """
 Replace symbolic constants with their literal values
 """
@@ -667,7 +676,7 @@ end
 
 function get_cmap(sys, exprs = nothing)
     #Inject substitutions for constants => values
-    cs = collect_constants([get_eqs(sys); get_observed(sys)]) #ctrls? what else?
+    cs = collect_constants([collect(get_eqs(sys)); get_observed(sys)]) #ctrls? what else?
     if !empty_substitutions(sys)
         cs = [cs; collect_constants(get_substitutions(sys).subs)]
     end