Final Cut Pro X and BlackMagic Video Output Devices - Playback Stutter

Hi all

I have a very frustrating and bizarre issue with FCPX and using BlackMagic output devices with the A/V Output feature. I have searched the internet far and wide for an answer and even though a few (very few) people had similar problems no one seems to have resolved it. BlackMagic told me they have never heard of this problem and that it is probably a problem with Final Cut itself.

The problem has been going on for years, ever since around version FCP 10.4.1. First it was on my 2013 8-Core Mac Pro and now it is the same on my brand new Mac Studio M1 Max. It happens with my BlackMagic UltraStudio 4K 2, UltraStudio Mini Monitor 3G and now with my brand new UltraStudio Mini 4K as well. I have tried different storage devices, splitting my caches and projects, different formats, codecs, frame rates, resolutions, various projects, fresh installs, plugin removal, etc. The problem persists with basically any kind of set up and with every version of FCPX and Mac OS since 2019 as long as one of the BlackMagic devices are enabled for A/V Output.

So here is the problem. Randomly when I press play the video playback will stutter (audio starts fine) for a few seconds and then playback will continue smoothly. Sometimes this happens once every few hours, sometimes it will happen every single time I press play. As soon as I disable A/V Output the problem goes away completely. Weirdly however on my 2019 13 Inch MacBook Pro I almost never have an issue with any of the output devices.

I consider myself a fast editor and it’s one of the many reasons I almost exclusively use FCPX, but with this issue it is almost impossible to get any work done without frustration, let alone embarrassment in front of clients.

Has anyone come across this? It is driving me insane. Thanks so much!