I have a couple of issues since updating to Photoshop CC 15.1 ...
Firstly, each PSD I open shows missing fonts even though I have Font Book open and the relevant font family is active.
And even though I select each font instance and "Resolve fonts", I get this same dialogue box EVERY SINGLE TIME I open the very same PSD which I find a bit annoying. I thought I had "resolved" them the first time I opened it?!
Could someone shed some light on why this happens and how can stop getting this prompt?
Most likely these are TypeKit fonts and for some reason you are no longer logged into your account when you next open the PSD. If you log out of your account you disable the fonts, which would cause the behavior you are seeing.