Hi
am having similar issue and i was wondering if possible for you to post the set up that you have with the Ocatrack as the master and Ableton as the slave (how is this done?) am using the Midex 8 as interface but am having difficulty getting it staying stable any help would be appreciated
I changed from Ableton Intro to Ableton Standard and this seems to have done the trick. Ableton is master for sync and transport - OT receives midi through RME babyface, A4 and AR via USB.
I know this doesn’t make much sense, but I have no more sync probs.
Not a chance! that’s why I need a drum machine!! 
You can use the tempo nudge trick to sort it though. For me, the accuracy of 135bpm for example on two machines is never spot on, they will definitely drift over time… Depends on how long their running together before restarting I guess.
Ableton actually does this when clocked from an external source, it knows yr computer is crap and ignores fast fluctuations. Before I had the modular and expert sleepers Es3/ES5 combo, I set Ableton as slave and took advantage of this, it was pretty good really but not perfect.
Oh yeah I aint arguing that, it’s a useful skill. 