This crash is still happening. Regenerated a track with only 3 instruments, all of them in normal time.
The instruments are:

3496 acoustic bass
3058 acoustic guitar
3142 5 string fiddle

Crash occurs when I regenerate the track. Typically happens after several regenerations. The problem report my Mac generated says it's an
EXC_CRASH (SIGABRT)
Exception Codes 0x0000000000000000, 0x0000000000000000
Exception Note: EXC_CORPSE_NOTIFY

Not being a programmer I don't know if this is sufficient info. However, every time the crash occurs it generates the "Band-in-a-box quite unexpectedly" message with prompts to report it to Apple.

I'm running a 2019 iMac with 16 GB of memory and my OS is Catalina, version 10.15.7