Solved for us.
Ours wasn’t a framerate issue or any kind of audio problem (or at least not as described in the replies). The devices are working fine. Not a driver issue. None of the solutions here worked.
Although to be fair, qubodup’s and MrCorleone’s solutions may work, I just didn’t feel like trying to figure out a whole slew of new commands + new software+ split every video into a video and audio.
I found a much simpler solution.
What finally slotted it was just converting the videos (TS format) to MP4 (what we upload at the end) using Handbrake
(download here: https://handbrake.fr/downloads.php --handbrake gives you a straightforward GUI and it’s free).
Do note, we lost the first few audio seconds on a few videos. No idea why but nothing happens in there anyway for us so no big deal.
Use handbrake to convert the video to whatever format you need at the end of the process, then use shotcut to edit+export and as best as I can tell, it’ll work.
I think there’s something flawed in how shotcut converts video file types, resulting in a desync. (took forever to narrow this down, LEARN FROM ME!)
So don’t use shotcut to switch video formats and you’ll avoid syncing issues – is my hypothesis confirmed in our gaming videos at least.