With OT, bugs and errors usually come from a wrong comprehension of what is going on. Trust me, we have all been there.
This is extremely hard to tell, from the information you have given so far.
We have no clue what your comprehension of synthesis or OT is, neither, so bear some out-of-track remarks…
Let me rephrase what I was talking about with the phasing thing, it might give you some light to understand what is going on.
Let’s assume you have Track 1 and Track 2 playing, all other tracks set vacant and Track 8 being set as Master.
On track 2, you have a regular sample playing, e.g. a kick.
On (FLEX) track 1, you are playing the Recording Buffer 1, that is recording Track 8 set as master.
If for some reason the waveform on Track 1 is inverted, Track 2 would be exactly cancelled if Track 1 was playing without any delay.
In reality, there is necessarily a slight shift between recording track 8 and playing back the recording buffer, so some frequencies are not totally cancelled, but you would still degrades the sound.
I’m not saying this is what is happening, but maybe it’s close enough.