I have done that
Unfortunately re-enabling the GPU after the latest driver install causes the problem to recur
What is the reason for wanting to have this option ticked?
While I will hardware calibrate my monitor soon
Go ahead and do it now, you most likely have a broken monitor profile.
You can, as troubleshooting and as a temporary fix, set the monitor profile to sRGB.
If the problem goes away, the the monitor profile is the problem.
Waiting for it to arrive. Why would doing this change the appearance in 1 module only anyway? I assumed it would simply alter both views in the same way.
Does one module use the calibrated profile and the other bypas it?
The develop module in LR uses a variant of ProPhotoRGB and the Library Module is displaying the previews which are AdobeRGB it is necessary for you to create a hardware created Monitor Profile.
Although I don't really understand this fully I will do that as the next step and feedback accordingly
Spyder 5 Pro calibrator turned up today
After monitor calibration I can report the following
On turning back on the GPU in Edit > Preferences the Difference in color and tone between the modules is no longer evident to my eye
ie the issue is resolved.
As a bonus most of my developments of RAW files look OK
Ill still reset the default settings for my camera though I think
Thankyou to all above who helped me work this through