I don't know what's responsible (possibly because I installed some betalabs stuff) but the credentials problem seems to be happening every time the phone is restarted.
Not a big issue for me, being able to change to silent overnight is more important so I've taken out the power saver from the rules. Possibly a stupid question - although 'power save' mode might not be accessible as such, is it possible to access the actions individually (e.g. screen brightness) or are they protected in the same way?