OK, something IS going on here I think. I tried 4 different files and get the same results as you. Amplitube shows connected, but does not produce the patched sound. Default BIAB sound plays. And, after reopening and playing the file (no Amplitube sounding) when I click the 'Stop' button I get an 'Access Violation' and BIAB freezes. Have to shut it down. Reopen, remove Amplitube VST, plays fine, stops fine.

I'd open a support call and have them remote into your PC and experience what you are ?

The file I tested days ago works just fine ! So there is a parameter or setting in that song that does not cause the issue..weird.