My suspicion is one of the clients drop follows that don't have a relay associated in their follow tag. But haven't figured out which client that is. Did you add a follower on a different client than the one yesterday?
Discussion
I had predominantly been using Amethyst, but moving more and more towards Iris as of late. I followed one new person today via Iris and that's when I noticed my follow feed was essentially empty, and only displaying events from that one person. That's when I found the issue, just one single follower.