Windows 10, LR 7.4. After the upgrade, when I try to check the sharpness of an image at 1:1 it appears soft.
If I go back to Library modde zoom to 1:1 the image appears sharp
The library uses a different preview than the develop module. Maybe you have a problem with the ACR cache. In preferences - performance you can purge it. If that does not help, turning off the use of the graphics processor in the same preferences tab may.
Thank you Johan, that appears to have fixed the preview issue.
I clear the cache, and restarted LR, trying it with and without using the graphics processor. Focus to check sharpness at 1:1 appears to be working OK now.