This may not be anything to do with what you are talking about but I have Pams as my main clock and the Midi out controlling my Beatstep pro, while playing i see the BPM change on the beatstep and can hear the slowdown in tempo. As far as i can see i do not have any Swing or probability set on the beatstep and I never have an issue with Pams swaying about as its rock solid.

Enjoy your spare HP, don't rush to fill every last space, this is not like filling sticker books. Resist the urge to 'complete' your rack, its never complete so just relax.

https://youtube.com/@wishbonebrewery