fix: fix check for observed quantities in initial values

Author: AayushSabharwal

src/systems/diffeqs/abstractodesystem.jl

@@ -797,7 +797,9 @@ function process_DEProblem(constructor, sys::AbstractODESystem, u0map, parammap;
     varmap = canonicalize_varmap(varmap)
     varlist = collect(map(unwrap, dvs))
     missingvars = setdiff(varlist, collect(keys(varmap)))
-    setobserved = setdiff(collect(keys(varmap)), varlist)
+    setobserved = filter(keys(varmap)) do var
+        has_observed_with_lhs(sys, var) || has_observed_with_lhs(sys, default_toterm(var))
+    end
 
     if eltype(parammap) <: Pair
         parammap = Dict(unwrap(k) => v for (k, v) in todict(parammap))