diff --git a/src/problems/daeproblem.jl b/src/problems/daeproblem.jl
index 6134923d4d..d98e275f17 100644
--- a/src/problems/daeproblem.jl
+++ b/src/problems/daeproblem.jl
@@ -72,7 +72,7 @@ end
         eval_module, check_compatibility, implicit_dae = true, expression, kwargs...)
 
     kwargs = process_kwargs(sys; expression, callback, eval_expression, eval_module,
-        kwargs...)
+        op, kwargs...)
 
     diffvars = collect_differential_variables(sys)
     sts = unknowns(sys)
diff --git a/src/problems/ddeproblem.jl b/src/problems/ddeproblem.jl
index 45af3edddb..4fb9b3f37b 100644
--- a/src/problems/ddeproblem.jl
+++ b/src/problems/ddeproblem.jl
@@ -66,7 +66,7 @@ end
     end
 
     kwargs = process_kwargs(
-        sys; expression, callback, eval_expression, eval_module, kwargs...)
+        sys; expression, callback, eval_expression, eval_module, op, kwargs...)
     args = (; f, u0, h, tspan, p)
 
     return maybe_codegen_scimlproblem(expression, DDEProblem{iip}, args; kwargs...)
diff --git a/src/problems/jumpproblem.jl b/src/problems/jumpproblem.jl
index 28de46c35f..dd3fd9ba1c 100644
--- a/src/problems/jumpproblem.jl
+++ b/src/problems/jumpproblem.jl
@@ -80,7 +80,8 @@
     end
 
     # handle events, making sure to reset aggregators in the generated affect functions
-    cbs = process_events(sys; callback, eval_expression, eval_module, reset_jumps = true)
+    cbs = process_events(
+        sys; callback, eval_expression, eval_module, op, reset_jumps = true)
 
     if rng !== nothing
         kwargs = (; kwargs..., rng)
diff --git a/src/problems/odeproblem.jl b/src/problems/odeproblem.jl
index 6726322907..bc8b9cf701 100644
--- a/src/problems/odeproblem.jl
+++ b/src/problems/odeproblem.jl
@@ -75,7 +75,7 @@ end
         eval_module, expression, check_compatibility, kwargs...)
 
     kwargs = process_kwargs(
-        sys; expression, callback, eval_expression, eval_module, kwargs...)
+        sys; expression, callback, eval_expression, eval_module, op, kwargs...)
 
     ptype = getmetadata(sys, ProblemTypeCtx, StandardODEProblem())
     args = (; f, u0, tspan, p, ptype)
diff --git a/src/problems/sddeproblem.jl b/src/problems/sddeproblem.jl
index e1cc00b2a7..0e3201c1d1 100644
--- a/src/problems/sddeproblem.jl
+++ b/src/problems/sddeproblem.jl
@@ -68,7 +68,7 @@ end
     end
 
     noise, noise_rate_prototype = calculate_noise_and_rate_prototype(sys, u0; sparsenoise)
-    kwargs = process_kwargs(sys; callback, eval_expression, eval_module, kwargs...)
+    kwargs = process_kwargs(sys; callback, eval_expression, eval_module, op, kwargs...)
 
     if expression == Val{true}
         g = :(f.g)
diff --git a/src/problems/sdeproblem.jl b/src/problems/sdeproblem.jl
index 1bc47118ff..83a050f7e4 100644
--- a/src/problems/sdeproblem.jl
+++ b/src/problems/sdeproblem.jl
@@ -78,7 +78,7 @@ end
 
     noise, noise_rate_prototype = calculate_noise_and_rate_prototype(sys, u0; sparsenoise)
     kwargs = process_kwargs(sys; expression, callback, eval_expression, eval_module,
-        kwargs...)
+        op, kwargs...)
 
     args = (; f, u0, tspan, p)
     kwargs = (; noise, noise_rate_prototype, kwargs...)
diff --git a/src/structural_transformation/utils.jl b/src/structural_transformation/utils.jl
index 02a9763226..67eb5b0c73 100644
--- a/src/structural_transformation/utils.jl
+++ b/src/structural_transformation/utils.jl
@@ -596,7 +596,8 @@ function _distribute_shift(expr, shift)
         (op isa Union{Pre, Initial, Sample, Hold}) && return expr
         args = arguments(expr)
 
-        if ModelingToolkit.isvariable(expr) && operation(expr) !== getindex
+        if ModelingToolkit.isvariable(expr) && operation(expr) !== getindex &&
+           !ModelingToolkit.iscalledparameter(expr)
             (length(args) == 1 && isequal(shift.t, only(args))) ? (return shift(expr)) :
             (return expr)
         elseif op isa Shift
diff --git a/src/systems/callbacks.jl b/src/systems/callbacks.jl
index cf9c53e610..a4f39243d9 100644
--- a/src/systems/callbacks.jl
+++ b/src/systems/callbacks.jl
@@ -63,7 +63,8 @@ Base.show(io::IO, x::Pre) = print(io, "Pre")
 input_timedomain(::Pre, _ = nothing) = ContinuousClock()
 output_timedomain(::Pre, _ = nothing) = ContinuousClock()
 unPre(x::Num) = unPre(unwrap(x))
-unPre(x::BasicSymbolic) = (iscall(x) && operation(x) isa Pre) ? only(arguments(x)) : x
+unPre(x::Symbolics.Arr) = unPre(unwrap(x))
+unPre(x::Symbolic) = (iscall(x) && operation(x) isa Pre) ? only(arguments(x)) : x
 
 function (p::Pre)(x)
     iw = Symbolics.iswrapped(x)
@@ -797,16 +798,34 @@ function add_integrator_header(
         expr.body)
 end
 
+function default_operating_point(affsys::AffectSystem)
+    sys = system(affsys)
+
+    op = Dict(unknowns(sys) .=> 0.0)
+    for p in parameters(sys)
+        T = symtype(p)
+        if T <: Number
+            op[p] = false
+        elseif T <: Array{<:Real} && is_sized_array_symbolic(p)
+            op[p] = zeros(size(p))
+        end
+    end
+    return op
+end
+
 """
 Compile an affect defined by a set of equations. Systems with algebraic equations will solve implicit discrete problems to obtain their next state. Systems without will generate functions that perform explicit updates.
 """
 function compile_equational_affect(
         aff::Union{AffectSystem, Vector{Equation}}, sys; reset_jumps = false,
-        eval_expression = false, eval_module = @__MODULE__, kwargs...)
+        eval_expression = false, eval_module = @__MODULE__, op = nothing, kwargs...)
     if aff isa AbstractVector
         aff = make_affect(
             aff; iv = get_iv(sys), warn_no_algebraic = false)
     end
+    if op === nothing
+        op = default_operating_point(aff)
+    end
     affsys = system(aff)
     ps_to_update = discretes(aff)
     dvs_to_update = setdiff(unknowns(aff), getfield.(observed(sys), :lhs))
@@ -871,10 +890,10 @@ function compile_equational_affect(
             p_getter = getsym(affsys, ps_to_update)
 
             affprob = ImplicitDiscreteProblem(
-                affsys, Pair[unknowns(affsys) .=> 0; parameters(affsys) .=> 0],
+                affsys, op,
                 (0, 0);
                 build_initializeprob = false, check_length = false, eval_expression,
-                eval_module, check_compatibility = false)
+                eval_module, check_compatibility = false, kwargs...)
 
             function implicit_affect!(integ)
                 new_u0 = affu_getter(integ)
diff --git a/test/symbolic_events.jl b/test/symbolic_events.jl
index 856a97484f..d82bf8a5c1 100644
--- a/test/symbolic_events.jl
+++ b/test/symbolic_events.jl
@@ -1348,3 +1348,30 @@ end
     @test SciMLBase.successful_retcode(sol)
     @test sol[inner.p][end] ≈ 1.0
 end
+
+mutable struct ParamTest
+    y::Any
+end
+
+@testset "callable parameter and symbolic affect" begin
+    (pt::ParamTest)(x) = pt.y - x
+
+    p1 = ParamTest(1)
+    tp1 = typeof(p1)
+    @parameters (p_1::tp1)(..) = p1
+    @parameters p2(t) = 1.0
+    @variables x(t) = 0.0
+    @variables x2(t)
+    event = [0.5] => [p2 ~ Pre(t)]
+
+    eq = [
+        D(x) ~ p2,
+        x2 ~ p_1(x)
+    ]
+    @mtkcompile sys = ODESystem(eq, t, [x, x2], [p_1, p2], discrete_events = [event])
+
+    prob = ODEProblem(sys, [], (0.0, 1.0))
+    sol = solve(prob)
+    @test SciMLBase.successful_retcode(sol)
+    @test sol[x, end]≈1.0 atol=1e-6
+end