Are you using tqt3? I suspect the issue lies in the QVariant::nameToType method: it fails to recognize the tqt type names (TQ*) returning QVariant::Invalid.
Yes, I am using TQt3. I haven't built anything against Qt3 in quite a while. There are minor build issues using either.
Have you tried rebuilding from the beginning (I am presuming you are using GIT and not 3.5.13)?
Darrell