Looks as if Google+ was hit with a small bug (others reported a crash but Google+ is still running with no denial of service) After Google+ was celebrating their 5th year in service just a few days ago, users of the site have swarmed Google today with complaints regarding around their follower count. It seems, for what is seen right now, everyone is effected but luckily it's just a follower count and nothing more. My personal account was affected; I had over 12,000 followers but it seems on all my collections, and my personal profile itself, I either have a handful of followers or none.
Some new followers are visible but anyone who added someone else prior to the event may not be seen. Almost all of my followers were before the event and before the major Google+ UI update, some newer followers seem to not have been affected.
If you look in the "People" section on Google+, it shows your follower count in its entirety, it may be an error on the front end of profiles and collections.
Google has already been notified and is working on the issue.