This sounds like your DVR is creating faulty files. I’ve only had this (albeit when using Davinci Resolve) with a video where recording wasn’t stopped before powering off.
However - this was easily solved.
Before editing, I used a re-muxer to create a “good” video file, and then edited this.
A re-muxer? … a program that creates a new video from an existing one … usually to change some aspect of packaging and/or codec … but can be used to create a video with identical packaging/codec.
I’m Windows only - but I know some of these are multi platform …
- VLC Media Player (yes - it can do a lot more than just play video files!)
Easiest of those to use for this requirement (creating a good copy) is probably Handbrake … but most people have VLC
Select “Media” from the menu bar, and then “Convert/Save”
Select your source file
Click the “Convert/Save” button, and then select “Convert”
Select the required profile - probably the default (chances are .mov is alsi available on Mac)
Enter “Destination file” location and name, and then click “Start”.
Hopefully something from above will help.