Reply to TP 2 only sending one channel signal to Audio 2

Hi there,

I played a gig with the following setup two evening s ago:

MBP
Newly installed TP 2
Newly purchased Audio 2
Two MFs Spectras

No issues on the set.

Now I tried out a new mapping, imported it. Tried it. Works more or less fine. Audio outputs working fine.
I restart the computer and all of a sudden only one deck is sending audio output to Soundcard. First it was only channel A, now after another restart it is only Channel B. Audio settings are

Output Deck A
L: 1: Ch A left
R: 2: Ch A right

Output Deck B
L: 3: Ch B left
L: 4: Ch B right

I HAVE ABSOLUTELY NO IDEA WHAT IS GOING ON! Has anyone got an idea?