Same issue here, pbc is very inconsistent for me.
Sometimes it works fine, but sometimes I have to jump through a bunch of hoops of rebooting the Polybrute, or rebooting ableton, or connecting/disconnecting the Polybrute.
Unfortunately, I have the most issues here when trying to use pbc in the use case I originally imagined.
This is my only hardware synthesizer and the tracks I produce include many layers of synths, so I multi-track it all over the place.
For a long time I used software plugins, and appreciated the quick speed of switching active instances and editing parameters.
One thing that drew me to the Polybrute was what seemed to be the ability to switch between active pbc instances and recall all preset info and automation, getting me hardware sound and interface with much of the convenience of software plugins.
But in general pbc, even if it is working for one instance, completely falls apart when switching between active instances.
It either loses connection and tells me fetching metadata failed, or stops tracking MIDI, or reverts to default preset, etc...
Looking forward to a software update...