@Rys was aware of the issue early today but was busy tending to real life away from access and ability to address the LetsEncrypt self-renewal hiccups. It seems like he finally fixed things (at least for now) a little while ago. Thank you Rys!
FWIW, I had this same sort of issue happen previously on my other forums and it's really annoying when it happens, because typically everything just works, but when it doesn't it's always at the most inconvenient moments.