I have seen a couple issues like this on here, but all the fixes were from a year or two ago.
The issue seems to stem from the fact that my playfab window disappeared, and because of that I can't turn on server models, so all my scripts that use server models are throwing an error. ON your set up page, the documentation states "You can move the editor extensions anywhere you want but you must retain the directory structure when doing so. If the extensions panel stops working, this is often the cause." what can I do to repair the directory structure?
This has happened before, but its hard to tell how I fixed it, since the fix isn't working this time. Last time I did a couple reimportings and reinstallations of unity, which did nothing, but then I just tried building in visual studio, and that seemed to clean the error up for some reason.
I've tried reimporting everything, reimporting just the playfab packages (this causes all my packages to produce the same directory structure error) I've reinstalled unity, deleted the whole project and tried using the latest backup, and the error persists.