I've been trying unsuccessfully to install an add-on. Then I noticed that even the add-ons Blender came with don't appear.
They're in the add-ons Blender folder but then when I check for them in Edit - Preferences - Add-ons, none of them are there, including the new one I'm trying to add.
In the screen shot I narrowed the search to "mesh" but of course I also searched in "ALL" before. I have a feeling there's some problem with that whole folder.
The circled addon is the one I'm trying to install and the rest were there already, I assume they're the pre installed ones