For the benefit of the community...
Edward has taken a look at this and it turns out it is confined to consoles (phantom ZerOS doesn't have the issue). It has been logged on the system to allow the software team to investigate. Initially, this is at a low priority which is fair enough as it doesn't cause any actual harm.
Whilst looking at old show files and collecting screen shots to help with this I discovered something else which is worth knowing.
I loaded an old file but forgot which so I went into save to check and found it had a different name. I asked Edward about this and it turns out show files contain their original names and these are used as the default when you save them.
This means that, if you change the file name (in Windows for example) then it will revert to the original name when loaded into the desk.
@Edward Z88 is truly the fount of all ZerOS knowledge. Just wish I could copy & paste from his brain to mine😀