Please have a look at the following link and see if this applies to you:

https://www.vegascreativesoftware.info/us/forum/vegas-pro-19-update-4-build-532--134491/?page=5#ca839504

... particularly:

_________________________________________________________

fr0sty wrote on 3/14/2022, 7:34 PM

Hi! I've just updated to Build 532 and I have an issue when I try to render a video with MAGIX/AVC codec.

I used the same video and same render profile and it was ok with previous version.

Now, the render generates a 0 octets video file. I tried with nvidia NV or Mainconcept AVC : Same result! Any idea?

A few users have reported this already, and if I'm not mistaken, I think they have already identified the culprit and are working on fixing it. In the mean time, use Voukoder to do your renders. It's a free VEGAS plugin that does fast and fantastic quality renders.