failed to render video - VS Ultimate 2020

[wickedfatchance]

Corel videostudio Ultimate 2020 (upgraded 3/1/20 from ultimate x9 without any additional package down loads, checked for updates, none found).
I upgraded because suddenly VSx9 could not read .MOV files compressed into HEVC.
VS2020 did great with importing all video files and editing, but I have been unable to render a video with transitions, most of the time it sems to do fine without transitions, but sometimes that is failing, too.
Usually renders a video fine without transitions (tried in multiple Profiles), with transitions added it fails near the end of rendering (varies 79-92% also tried in multiple profiles), sometimes it does not even give me an error notification, it just stops (this has happened with and without transitions). Total finished video length right now is under 3 minutes.
without transitions - Error notification: Failed to read video, Error code 17200387
with transitions - Error notification: Unable to load library, Error code 19151:3:3

Video files (.mov and .mp4) have come from Iphone11, samsung phone and 2 camcorders. down loaded from DVD (Samsung phone .mp4), USB cable (camcorders) and USB thumbdrive (Iphone .mov) to my hard drive which has lots of free space.
Video data rate varies
Type of audio MP4

Operating System - Windows 10 Home (x64) Version 1909 (build 18363.657)
Motherboard: ASUSTeK COMPUTER INC. X99-E Rev 1.xx
Processor : 3.40 gigahertz Intel Core i7-6800K
Ram 32GB
Video Card : NVIDIA GeForce GTX 1060 6GB
Sound Card : NVIDIA High Definition Audio
Hard Drive Capacity : solid state 500GB and 2 additional drives 6000GB

[JEB]

Hey Wickedfatchance -
If it is any consolation I am getting nearly the same reaction from my VS Ultimate 2019. Like many other posters encountering this 19151:3:3 error message it seems to happen either about 10% of the way into a rendering, around 90% of the way in, or in my case, just as the rendering ends... and nothing. It does not so much as crash but just does nothing and gives an error message. It is as if no rendering occurred and there is nothing to show for it.
I tried running the same rendering on an older machine with an older version of VS and did not get the error message but it too stopped at the end of the render without any output, very frustrating. This older machine has never done this to me, so I do think it is something in the content of the video clips.