Solution that worked on my wife's S21+ with this issue:
Create a New Temp folder outside the DCIM folder and transfer a few photos/videos to this new folder. Access this folder from the PC, this way the DCIM/Camera wont kill the file recogniton. Cut/Paste those files to a folder on the PC and repeat.
Little time consuming but it worked.
When I plug my Galaxy S21 phone to my PC, the internal storage folders are empty. However, when I look at my files on my phones, I can see photos, downloads, etc. I used several different phone cords, cleared the cache and data in the camera, checked my computer for updates. What can I do? I really want to get the photos and videos off of my phone.