Ableton 10 buffer setting confusion

[Missionrec]

I am a long time Ableton Live user, enjoying V10 (final build) for now. I use a Lenovo Yoga laptop, i7-1050H, 16 gigs RAM, 2 external drives 1 on each thunderbolt 4 bus, Win 11 latest build.

I have a Yamaha UR22 Mk2, a PreSonus 1824c, and 2 Behringer x32 Racks.

My main live Ableton setup is a Kontakt piano with 3 synthmaster one pad sounds in layers, which I play live from a studiologic 73 controller. I control all part levels with an APC mini.

I have no pops and clicks, the system is solid and fine (fun!) with a 256 buffer on the UR22 audio interface. 15-25% CPU with Ableton system meter.

Neither the x32 or the 1824c can even come close to that buffer setting, with all the rest of the system identical. I get pops and clicks at any usable, and at some very unusable buffer amounts.

Ableton system meter stays the same.

I've tried multiple USB cables, have tried all the USB ports in the system, I always prefer the audio interface on its own mobo USB port directly on the laptop.

Anybody achieved a 256 buffer for live VSTi playing on an x32 Rack? That is the real goal.

Thanks for reading