We have a customer that can't link to our App. In their security settings for our app is says something like, "App folder is deleted", even though they have our folder listed under their "Apps" in their account.
We started seeing this Saturday, and it appears we have possibly 3 customers with the same issue. Did something change? How do we resolve this? We did try having them "x" the security/app entry, but that didn't help.
This can occur for API apps using the "app folder" permission, and it indicates that the user has deleted the app folder itself, e.g., via the Dropbox website, desktop client, mobile apps, etc.
It's always been possible for users of these apps to get in to this state, and I'm not aware of any changes to this. Further, note that re-adding a folder with the same name under /Apps won't re-connect the app, which may be the folders you're referring to.
To fix a user in this state, just as if they had unlinked the app entirely, the app should prompt the user to re-authorize the app, if they wish to continue using it. This will recreate an app folder for the app.