I was able to work all afternoon today with no crashes. I built two songs from scratch, and included repeats that allowed the program to add lines automatically. It worked ok. I didn't touch the instrument tracks however and didn't attempt to open the files I was working on when the program crashed before.

I also reset all options to the factory defaults.

I'll stay away from editing the individual tracks. That won't be a problem for me but I think it needs to be flagged by IT as a possible bug in 423.
Equipment: Yamaha 5'6" grand piano. BIAB for Macintosh 2017 --> 2020. MacBook Pro. Focusrite 2i2, Yamaha YC 88 keyboard

"Why do I have to go to school, Grandad? If I watch YouTube I'll know everything!"
- Grandson #3