Alarms sometimes don't work without an internet connection

More than once, I've noticed if I have an alarm in the clock app configured, and I have selected a song to play instead of a pre-included tone (apple music songs), if my iphone is offline when the alarm time comes around, it will not play.

The alarm will go off of course, but if no vibration has been configured and the audio is not a preloaded tone, it seems that the behavior WILL be that the iphone will just display the alarm screen, silently, for as long as it takes for the user to come around to it naturally (if the alarm is waking the user up, the UX breakdown is pretty apparent).

Has anyone else seen this? A warning in the clock app that picking a custom tone might make the alarm simply not work would seem to be critically necessary... my iphone is doing a worse job at this than devices I can find at the thrift store for pennies.