Potential bug - Thumbnail of video files not displaying in Dropbox folder

It's a lot of personal photos so I had to remove them. I believe I've only blurred unrelated details, or what my text description has covered. What details you would like to see? I am happy to provide them. Or if there's some way for me to send you the original screenshot privately.

The thumbnails are displaying alright in File Explorer at the same time. And refresh in either File Explorer or DirectoryOpus does not change anything. Reboot did not change anything. Also used clean-up tool to rebuild thumbnail cache, which did nothing as well.