ProTools MTRX studio - PT can't play, UA Apollo works fine

[windmillaudio]

I have a MTRX studio as my main interface, and have just formatted a new Mojave install.
Using the HD Native Thunderbolt as the playback engine, ProTools won't play. Stop button lights up and Play button flashes.
If I change the playback engine to my UA Apollo, ProTools plays fine.

I'm running PT 2020.11, and had installed the 2021.3 Avid HD Driver. Tried installing the previous 11.3.2 Avid HD Drive, and neither are working.

Dadman and PT are both set to 48kHz, internal sync.

Anyone seen anything like this?

[LDS]

Oh yes, I have seen that quite a few times.

My only suggestion is to check that the MTRX Studio in DADman is set to adapt to Pro Tools 1/2 (or Digilink 1/2 depending how it is labelled) under the synchronisation settings.

[windmillaudio]

Solved... I had tried the available HD Drivers from the Avid Site, but there's an HD Driver that comes within the PT installer. I had installed PT 2020.11 off site without the MTRX studio, so had forgotten about the HD Driver.
I then installed the Avid HD Driver 2021.3 once on site, and thus, problems.
Once I installed the matching Avid HD Driver 2020.11 in my case, to match ProTools, everything is working.