V5 cannot play same files as v4 even after patch

[stackoverflow13]

I had a situation like others where v5 would crash. Thankfully I was sent a patch which fixed all those problems, however I have a new one.
When playing a particular video file (mkv) on v4 all was well. once upgraded to v5 & patched, the same video file can no longer be played. TV shows cannot play this type of file, (or file not supported) can't remember which.
Also the reverse function is often hit or miss sometimes working, sometimes crashing & having to start playback again
Sorry don't have logs as I went back to v4.
specs:
dedicated machine Core i7 8gb ram, win10 pro, wired Gb ethernet