Ever since the update to Big Sur it's been a nightmare for me. My biggest issue is now when I go from develop mode into library mode, only SOME of my images are off color and incredibly muted. They export in proper color and appear in proper color when in develop mode, but for some reason a handful show up muted in the library mode. I've never before had this issue before the Big Sur and recent lightroom update. This is happening in all of my catalogs so it's not one particular photo set. Has anyone experienced this?
I have been experiencing the same issue in the same circumstances (macOS Big Sur 11.0.1 and LR Classic 10.0), yet the "muted" version only appears during a split second and then reverts to the correct (edited) version. It doesn't seem to happen on every photo, so there must be something happening when specific conditions are met, but so far I have been unable to find which conditions. It seems to me to be an issue with the previews or the preview cache files.
However, what we could try to do to find the culprit, is the following:
1. Export a particular folder or collection of photos that are exhibiting the problem, as a catalog, EXcluding the existing previews.
2. Open that new catalog in LR Classic.
3. Manually create new (standard sized) previews.
And then see if the problem still exists with the photos that got "muted" in the Library module using the "old" catalog. If the problem is gone, the issue seems to be related to the preview cache files, me thinks...
Exporting a number of photos that exhibit the problem as a catalog and then testing that new catalog is a safe way to try and find the cause, as it prevents the need to delete the preview cache files of the catalog(s) you are working on.