AMD 6700x, 5900x , 64gb RAM, Windows 11, Vegas 20 (build 370)

Hi there. I keep getting a weird glitch when I render out footage. This is with h265 10 bit 60fps footage from a Sony a7siii, rendering using Magix AVC category with the AMD VCE encode mode, set for 4k output.

You can see the problem in this youtube demo clip here - the last few seconds:

I assumed it was a problem with the clip as it only lasts the duration of that clip. But if I swap the clip, I get exactly the same problem. Also, if I render from the start up to that time, it happens. But if I render from that clip to the end, it doesn't happen. It's also fine if I render just that region. But if I then slot that pre-rendered segment into the timeline, I get the same problem on the full render.

I've tried resaving the project and moving the whole set of clips further up the EDL, but nothing helps.

If I render with Encode mode of Mainconcept AVC then it goes away, but of course the render is much slower.

I'd be super happy to hear if I'm missing something obvious. But if anyone else has seen anything like this, I'd also be glad to hear to try and track down what's going on.

Thank you.