I'm still seeing the same rendering issues (freezes) when rendering with Vegas Pro 19 Build 643 that started with build 636. The only "solution" is turn off the File I/O NEVC decoder and legacy HEVC checkbox option prior to rendering and enabled it again for smoother video editing. Each time this requires a restart of the app which is a pain.
Initially, I wasn't having any rendering issues. I had about 10 successful renders. But by time I had 8 tracks filled in an edit, I started seeing the freezes occur during rendering. Once at 92% and several at 59%.
No transitions in this video, several masks. I reduce the size and reposition two of the videos in Pan and Crop. I'm using a saved LUT to color correct the one video track. The video is of an online chess match and has a cut for each chess move so about 80 in its six-minute length. All videos are raw 1080p and rendered the same NVIDIA/NVEC 29.97 fps X 1920X1080
Video edit image: https://flic.kr/p/2ntGAtc
Track 1 - Titles and Text entire length of video
Track 2 - Titles and Text entire length of video
Track 3 - Screen recording from PC
Track 4 - Gopro 1080
Track 5 - Gopro 1080 - Two masks
Track 6 - Gopro Audio
Track 7 - Vegas Noise - Texture 9 - entire length of video
Track 8 - Image (JPG) - Entire length of video
This is the YouTube video
Nvidia GTX 1070, Windows 11, i7 series 7000 CPU
There's enough improvement to this build, I can live with this workaround and don't plan on going back to an earlier version. The video editing seemed very stable.
Update: - I have had some successful renders (of the same video file) with the File I/O set to the video card and legacy decoding checked, so it is not repeatable problem. One positive aspect of setting the File I/O to "None" is the video renders faster (15 min. versus 18 min.)