Error: Attempt to process /Script/MyModule/ before it has been added

Hey, i have a runtime module that implements a K2Node and some logic. It works in the editor and standalone game. But as soon as i try to call functions from my c++ code, i get a crash and the following error:

Fatal error: [File: Engine\Source\Runtime\CoreUObject\Private\Serialization\AsyncLoading.cpp] [Line: 734] Attempt to process /Script/MyModule/ before it has been added.

I tried different loading phases, but that didn’t solve my problem. Does anyone has an idea what is causing this?