Thanks for your efforts and all the Kodi peeps.Thanks @Radsen
I've added you comment to the Kodi bug report. 19.3 has been released without the progressbar/duration timer fix. I missed the cut-off. (19..4 hopefully for the fix).
Goes to show users need to report a Kodi bug or it won't get fixed. Not surprising at all.
I thought I'd reported this ages ago but it turns out I did but the 'fix' then was to change my 4K TV refresh rate in Kodi. That fix worked back then but not with recent Kodi releases and I'd forgot to report the 'new' bug a second time!