Trouble with MIDI connections

So know I’ve got some bigger projects running,
the problem mentioned above is even more annoying.

I have to set the midi connections back more often then I can start recording something,
at least that’s how it feels.
When I pull out the iRig Midi Interface, all track that have been adressed to SampleTank are switched back to virtual midi, or sometimes accidently (thats how it seems to me) to some other app, that is running in the background. Why??

Does anybody have a clue about what I’m doing wrong or has the same problem?
Cheers