Some files are randomly made live when put into shot cut and methods to change them to usable files either only make a frozen screen with the audio or a file type that is super laggy in playback sense more common file types such as mp4 are not available
Make sure you have the latest version. https://shotcut.org/download/.
Older spec systems will give you problems.
Read https://shotcut.org/FAQ/#what-are-the-minimum-system-requirements
This is a stupid and useless bug report. I have done all I am willing to do to support the total garbage you try are trying to feed it.