I'm running 5.1.1. Seems to be the latest version. I've disabled the "Limit Login Attempts" plugin, as that seems to be the only one that could remotely be related to WordFence.
I should point out that I think WordFence is pretty damn amazing and I'm impressed it's offered for free, so please don't take my issue with it as meaning I'm not a fan. I just need to understand what keeps breaking. :-/