Hi,
To avoid issues, I have a script based on the free app ffmpeg (https://ffmpeg.org) to convert every video to a friendly format for Nuendo, following the guidelines provided by Steinberg (https://helpcenter.steinberg.de/hc/es/articles/115000808250-Video-support-in-Nuendo-Cubase-and-Dorico). In my opinion, H-264 is good enough for my needs, so I use to convert everything prior to start working with just this command line (it works in every OS):
ffmpeg -i sourcefile.mp4 -x264-params keyint=1:bframes=1:ref=1:b-pyramid=0:weightb=0 -acodec aac -ar 48000 -b:a 320k targetfile.mp4
The source file could be almost any video format available. The list of source file formats and codecs for ffmpeg is here:General Documentation
Regards