Thumbnail issue

I am having the same issue - after wasting an hour searching the internet I see this is a common problem that has been reoccuring since at least 2015 and I guess 'they are working on it' again.  Just enough agony to keep making me crazy

Having exactly the same issue since receiving the latest update 2021.001.20138.

I have noticed some odd behaviour though. Normally when you open Windows Explorer the address bar has a solid green bar that scrolls along the address bar to refresh the thumbnails, this no longer happens, (THIS MAYBE JUST A NEW THING WITH WINDOWS 10 ITSELF AS THIS DOES NOT HAPPEN EVEN IN PICTURES FOLDER NO LONGER). Also on some folders that contain PDF files the folder as contents thumbnail, when opening the folder a couple of the files have a PDF thumbnail but when you close the folder then reopen the folder the thumbnails have gone on the files that were previously there and only show the standard PDF thumbnail.

I have disabled the thumbnail in Windows Explorer option in Adobe acrobat Reader DC settings, restarted and re-enabled with no effect on the issue. I have also re-installed the Adobe acrobat Reader DC also with no effect and a repair installation option again with no effect on issue.

I have the same problem. Latest Acrobat update breaks the Explorer thumbnails.