Are you binding to dispatchers ate begin play?
Check if all casts are valid. I had similar problems, because of loading order. Things load differently in standalone game than in editor one. Sometimes actors load bit slower (or faster), and not all references are ready yet. Some time ago everybody was adding that 2 sec delays for this problem.
Also if your level is streamed, when it unloads actor and reloads it, actors are reset to default state. Not sure if binding to events/dispatchers survives it or not. I never use level blueprints.