If a (non-admin) user edits his profile, all media entries are deleted. I believe this is due to the call to CUser::updateMedia() on line 172 of users.php. CUser::updateMedia() deletes all media for the specified user(s) on line 911, and nothing is re-inserted, as the media list is blank for non-admin users.

I mark this as a blocker, as I have had several users stop receiving alerts with no warning or notification. The users only find out that they have missed alerts through discussions with others who have received them.