Hi Rob
I had a number of issues myself on BigSur that improved once I moved to Monterey. Not sure if that upgrade path is there for you.
I also found that repository dialog boxes wouldn't fill until I'd resized them using the mouse. That seemed to be enough to get them 'aware' so may be try something similar?
Finally, 9.3 will run on Java11 so it might be worthwhile givi ng that a try.
Regards