Tried to log in on my Muso 2 and my QB2 using my iPhone and iPad, but got login error messages in all cases. I can log in via the Qobuz app and cast to my Naim devices via Qobuz Direct.
Also, no problem logging into Qobuz on my Wiim streamer using the Wiim app.
Morning after edit - Looks like logging out from Qobuz on the Naim/Focal app and then logging back in will fix it.