dumpcpp: The generated code can sometimes have the wrong offset for the slots and therefore fail to find one in the metaobject. It is not clear to me as to why this actually happens but attached is a reproducible case for this.

The tlb attached can be used to generate the code via dumpcpp:

dumpcpp IOM.tlb -o IMO

If you look at the iom.cpp file, specifically:

qt_meta_stringdata_IOM__IHttpServerConnectionComIncoming()

then the Login() slot in particular seems to be offset in the wrong place because if you try to use this function like:

IOM::IomFactory *factory = new IOM::IomFactory; 
IOM::IHttpServerConnectionComIncoming *conn = factory->CreateWinAuthHttpServerConnection("url" ,"name"); 
conn->Login()

then it will fail with the following assert:

ASSERT: "id < 0 " in file qaxbase.cpp line 3718