Found another one - seems to be my week.

Any family exported from a project using a name including "." will be changed and the . replaced with -.

For example - we had Int. HM Door.rfa. This exported as Int- HM Door.rfa. Not noticing this when dropped back into the project I ended up with a similar family with the wrong name. And of course the old families were not updated.

I was wondering why I couldn't update any of my doors in this project.