I use the new Lightroom, not classic, and I continually update it. Many of my images was synced to the cc cloud storage. But I decided to remove them from the cloud, since I really have noe use for them there, and Lightroom constantly reminded me I needed to upgrade my cloud storage.
Again, I do not know if this is what caused the problem. I only see now that a lot of my more recent images now only show a low resolution image when I open and work on it in Lightroom. On the Info-tab I get the message that local sync status is pending. See attached image.
The local files are still in the folders. Stored on an external hard drive.