So today I am looking at directories in my NAS and I open one that I had not opened before in QU that had 92 RAW files. The phone rang and I talked for 10 minutes and noticed that all the thumbnails still said loading. Just moving the slider made them all appear.
So I opened an image in the editor and messed around, came back to the folders and they all said loading again. When I moved the slider to look at more images and hopefully get the thumbs back, here is what I got. Clicking OK made the thumbs come back.