[mangoustine]

OK. So, why is the RTAS version perfectly in sync ? By the way, when I insert a mulit-mono plugin (because there's no multichannel version), I expect it to be in sync...

Also, you can try this :

1) Create an Aux track
2) insert a TDM multi-mono signal generator
3) if you have an external phase meter, you should see it's not in phase
4) insert a TDM multichannel Phasescope => now it's in phase
5) Make the signal generator inactive, then reactivate it => not in phase
6) switch signal generator to RTAS => in phase
7) switch it back to TDM => not in phase

I don't think this is a normal behavior... but I might be wrong.