revert remove observed

Author: vyudu

src/systems/abstractsystem.jl

@@ -648,12 +648,12 @@ function complete(
         if has_continuous_events(sys) && is_time_dependent(sys)
             @set! sys.continuous_events = complete.(
                 get_continuous_events(sys); iv = get_iv(sys),
-                alg_eqs = alg_equations(sys))
+                alg_eqs = [alg_equations(sys); observed(sys)])
         end
         if has_discrete_events(sys) && is_time_dependent(sys)
             @set! sys.discrete_events = complete.(
                 get_discrete_events(sys); iv = get_iv(sys),
-                alg_eqs = alg_equations(sys))
+                alg_eqs = [alg_equations(sys); observed(sys)])
         end
     end
     if split && has_index_cache(sys)