Assert when replica is connecting in a QTest

I'm trying to add QTest to the Client/Server project I'm working on. The problem is that it crashes at the most basic init with the error:

ASSERT: "member.isValid()" in the file qsignaldumpler.cpp line 73

The call stack tells me it has something to do with

`QRemoteObjectReplicaImplementation::emitInitialized`. 

I was able to recreate the problem in a test project that has the same structure that the original. A lib project for the source and replica that contains all logic. An executable project for the server and the client. And for testing some *Test projects. The `ReplicaSourceTest` contains a server and a client. This was also tested and could be confirmed to have the same problem when running the server as a standalone application and running the tests only on the client. So this combination of both is simply for convenience. The Client successfully connect to the server like I did a million times the last 3 years. But with this setup, it crashes because of an invalid member. Any ideas?