Hi,
I have had a similar issue once, and it was Chrome extensions causing this. Have you tried playing the video using a brand new account with no chrome extensions, you could use a incognito window but some extensions still are used ( that caught me out )
Then you may need to remove extensions one by one to figure out which one is causing it. There's also a setting in Google admin to reset user's data, I can't recall the settings so be careful and maybe have a look at the affected user's settings on G Admin.
Hopefully this helps, apologies if not!
Cheers.