[Ville Tanttu]

hello

Try This: to change 64 bit to 32 bit.
FCP is 32 app, so all these kind of super random bugs seem to appear with new systems…
This really improved performance in my system – and the same kind of problem as u have disappeared- with similar Mac setup.

I hope this cures it:

all the best

Ville

To temporarily switch the kernel:
On bootup, hold down the “3” and “2” keys to switch to the 32-bit kernel. The system will continue run in this mode until the system is rebooted, reverting back to 64-bit kernel. Inversely, holding down the “6” and “4” keys upon bootup will force the 64-bit kernel to load.

“To persistently toggle your Mac Pro to the 32-bit kernel follow the steps below.
NOTE: These scripts toggle the nvram, and the changes require authentication. You must have a password on your system, blank passwords will not be accepted.

To switch to the 32 bit kernel, download and unzip the attached file and run the switchto32bit.command file.
To switch back to the 64 bit kernel, run the switchto64bit.command file, also included in the attached zip file.”

https://avid.custkb.com/avid/app/selfservice/search.jsp?DocId=375771