I am having a similar issue.
I have a scheduled power off/on and while I think it always powers off (sleeping so don't check it), it doesn't always power on. I used to have my alarm and power on at the same time, so thought this could be an issue. I changed power on for 10 minutes before my alarm is due, but several days the phone hasn't come on. This morning for example, woke up 5 minutes before the alarm, picked up the phone and it was off. My phone is always unplugged - i never charge it at night. Not sure what the battery charge was each time.
I will keep an eye on this to see if I can figure out why it doesn't come sometimes, but would be good to know if other people are having this issue, and if it's some kind of bug that can be fixed (setting an alarm shouldn't be something that interferes with the scheduled on&off)