I am happy to report that this issue looks to have been resolved.
The roll back took a bit of time to do, and I am still not sure that I did it fully correctly. However it did the trick.
I also note that there were some subsequent updates to both the Mesa libraries, and xserver-xorg-video-amdgpu driver, amongst which was a fix.
Thank you, Sebastien, for all your help. it is very much appreciated.
Many thanks, Mark.
I am happy to report that this issue looks to have been resolved.
The roll back took a bit of time to do, and I am still not sure that I did it fully correctly. However it did the trick.
I also note that there were some subsequent updates to both the Mesa libraries, and xserver- xorg-video- amdgpu driver, amongst which was a fix.
Thank you, Sebastien, for all your help. it is very much appreciated.
Many thanks,
Mark.