Issue with HEVC transcodes failing if their are more than one going at a time

When you render more than one HEVC file at the same time, FCPX or Compressor fails. So this happens when FCPX and Compressor try to render HEVC at the same time or when you set up multiple HEVC exports/files at the same time and have additional Compressor instances in the preferences. Happens with 8-bit. Can't remember if it happend with 10-bit. Tested on multiple Macs. I submitted a ticket about a month or so ago to Apple. Hopefully, some others can test this and submit tickets to Apple to get this fixed.

Tested on iMac Pro Intel 18core & Macbook Pro 2009 Intel (Catalina & Big Sur). FCPX 10.6.1, Compressor 4.6.

So, any 2+ timelines, export as HEVC, all exports fail?

EDIT: Just exported 2 timelines from the same event - selected both, hit Cmd E, set output format to Apple Devices, Codec HEVC 8-bit, Resolution 1080, no chapter markers.

Both files completed with no errors. M1 Mini, everything current.

Edit 2: Electric Boogaloo - Compressor will only allow one instance on the M1 Mini, so I guess this isn't terribly useful info.

Edit 3: Running Compressor and FCP, with both apps rendering to HEVC simultaneously, no errors.  Could be just an Intel thing.

To further clarify the encoding has to be in parallel/concurrently. It works fine in sequence.

In Compressor, you can only have more instances if you have lots of ram and CPU. With our iMac Pro we can run 7 instances.

For most people to test, start an HEVC share from FCPX. Then begin an HEVC transcode at the same time from Compressor. Compressor will fail. If you do it in the opposite order fCPX will fail. Make sure the video you are using is at least a few minutes long.

I hope to test on my new M1 Max Macbook soon.

Tried both (start FCP first, then Compressor / start Comp first, then FCP).

Both encodes finish successfully on M1 Mini / Monterey / everything up to date.