Hi craftycurate. Thanks for reporting this one, i can confirm what you say.
Sorry for the inconvenience, i'll report it to dev colleagues right now, and will keep you aware.
Best,
EDIT : I was mistaking ! actually when you're in arturia picks playlist, a-z sorting is just unavailable when you're in a playlist! quit this playlist , and the feature will appear again .
please tell me if it's ok for you.