No, the problem persists after I’ve connected it directly to the TV and rebooted. (And one of these days I am going to take some pictures so you can see quite how difficult it is to switch the cables around in my living room. 
)
To the best of my knowledge, nothing interesting has happened to the TV itself in the past 24 hours.
It occurs to me, I did have have to power-cycle the Vero 4K+ earlier today after it froze up. I didn’t notice the problem immediately after that, but it could be that I played a couple of unaffected files first and only came to one that exhibits the issue later, so there might be a connection. Is it possible some setting or file got corrupted?
If you wanted to temporarily blow out the Kodi folder to test it as mentioned earlier…
sudo systemctl stop mediacenter
mv ~/.kodi ~/kodi.bak
sudo systemctl start mediacenter
If need you can restore:
sudo systemctl stop mediacenter
mv ~/.kodi ~/kodi.bk2
mv ~/kodi.bak ~/.kodi
sudo systemctl start mediacenter
If your original setup was restored as expected and you want get rid of the unneeded clean install you can delete that with the following command.
rm -r ~/kodi.bk2
This of course is going to knock out your sources and library but you can just use the file manager in settings to play some files to test without the extra setup.
If you wanted to do just the guisettings then you would do the same thing but instead of renaming the .kodi folder you would be doing ~/.kodi/userdata/guisettings.xml (assuming your not using profiles)
EDIT: I updated the instructions to ones that work correctly.
Getting a little late tonight, but I will definitely try that tomorrow.
Well, the good news is that going through this process has fixed the playback issue. The bad news is that “restoring” didn’t actually restore anything, so my libraries seem to be gone for good and all settings and skin customisations permanently gone too.
Better than it not working, I suppose.
I would say there should be hope.
Can you post the output of ls -lah /home/osmc
For me it looks there were some spaces in the above commands which may have let to moving wrong folders.
They are not. Sorry, I pulled that from someone else and did not test it first. Your info is still there. To fix it just do the following…
sudo systemctl stop mediacenter
mv ~/.kodi/kodi.bak ~/
mv ~/.kodi ~/kodi.bk2
mv ~/kodi.bak ~/.kodi
sudo systemctl start mediacenter