Also tagging
@ErikGrim over this.
I have reasons to believe that the crash when connected to power adapter is occurring due to "photoanalysisd" daemon. I have seen this daemon take up well over 100% CPU, and now that my People have been analysed in Photos, I found my computer to wake up normally even connected to power.
Simply put, what is happening is that the said daemon is overheating the computer when the computer goes idle and not in use. So, what seems like a computer sleeping and not waking properly is in fact a thermal shutdown event.
As always, these are my observations on my computer, I am in no position to claim that this exact thing is what is causing the wake issues with others. To all those who are facing this issue, please take note of two things:
1. Is the computer connected to power?
2. In the Activity Monitor, do we have a photoanalysisd daemon using up the CPU?
In my case, this was it, and has now hopefully solved the issue. I have come back to my connected-to-power computer a while ago and it woke up. I have additionally let the computer sleep for 30 minutes on power again, and it woke up with a keypress.
Needless to say, I am submitting a fresh feedback that is specific to this particular observation.