@Mariah22pl I have not personally had any problems replacing existing files with new/different ones.
Plex detects the new files and detects the old files have been removed, and empties trash after rescan also.
As far as playback of new files, not noticed any problems.
As far as analysis/thumbs/etc, I have not noticed any problems.
edit: that said, I am generally replacing old files with new files of a different name, not replacing files with the exact path/filename (ie over writing existing file).
I’ve been advised that plex should automatically regenerate analysis/chapters/thumbs/previews/ad-detection (accordingly to however the library/scheduled tasks are configured, of course).
If anyone has logs or other evidence to the contrary, please feel free to provide it, so it can get resolved.
as far as the original post with the black screen/spinning circle… logs logs logs.