Sorry I can't help. I wish I was there.
My trouble shooting would probably involve by-passing all FX and soloing until I could get the two ouputs to behave identically. I would definitely open up Total Mix and check the levels on the different outputs. I usually use 7+8 rather than 1+2, but it shouldn't matter.
You might try doing a Total Reset in Total Mix. Options > Reset Mix > Total Reset.
I have definitely resolved many baffling issues with this simple method. Total Mix is cool and complicated and sometimes I just can't wrap my head around how the routing it working. Maybe I set some pair to loopback or something and it starts to get crazy. Just a tip.
Best,
Geoff