This is something that came up recently and I thought I would I would share in case you are running into the same problem. The scenario is this. A user is deleted from AD and then a profile import occurs on the SharePoint side. The user is still in the User Information List, because those users never get deleted. The user is then added back to AD with the same login and then another profile import occurs. Now there will be two users with the same login in the UserInfo table of your content database. One of them will be marked as deleted. Now you add that user to some SharePoint sites as individuals. Everything is fine and dandy until you run the profile import and SharePoint does it timer job magic. All of the sudden the user’s permissions are removed come the next day! Obviously, this can cause some real concern to you and the user. To fix it, do the following steps.
Delete user from UserInfo table in the site collection database (you may have to do this multiple times if they are in multiple site collections with different content databases).
Delete the user from the User Profiles in Central Admin (you might want to copy their profile info if they have any and add it back after the import).
Run a full profile import
That should solve the problem of users having permissions dropped.
#SharePoint #permissions #userprofile