I’m having exactly the same problem. I’ve read this post but tried it to no avail. It seems I can delete the schedule, but then when I go back out to clock it’s still there says tomorrow only or next day. Tap on edit/change itvthen says add schedule...???
yeah a bug to say the least! Also that the tones available under that alarm option and regular manual set alarm, should be the same! The other annoying thing is scrolling through the list of alarm sounds, every time change selection it plays the sample tone at full volume! Turn it quickly down, hear it select the next one and boom full volume!
To be honest, this sleep feature, along with the new self limiting volume feature, is starting to grind at my trust in Apple. I’ve always had iPhones but never had so many software issues than in the last 3 years... and iOS bugs! The testing is either not being done or not well enough. Apple used to be rock solid in stability...