I recently upgraded my mid 2011 Mac Mini to macOS High Sierra. I purchased the Magic Mouse 2 about a year ago, but really loathe the charging port on the bottom (unbelievably stupid design, but I digress). As such, I kept my old (original) Magic Mouse handy for when I needed to charge the MM2. I never had problems with this use case in OS X El Cap.
However, today when I tried to use the old Magic Mouse, macOS absolutely freaked out and neither of the bluetooth mice could connect. I had to use a generic Logitech USB mouse to "forget" both of MM (old and new), then I could reconnect the new MM after it charged.
So my question: is the original Magic Mouse unsupported in macOS High Sierra? Or perhaps I simply can no longer use the MM1 and MM2 interchangeably?
Update: Perhaps forgetting and re-pairing the mice was all that was needed..? Issue looks to be resolved now and I am able to use either mouse. This was just a leftover quirk from the OS upgrade I can only assume...?