Hello @juanpablo
unfortunately the current version (as of today) of the official M5StickC Plus library is still broken in regard of light sleep or deep sleep. The faulty function is SetSleep() which powers M5StickC Plus completely off (as you encountered) and therefore the system cannot wake from light sleep or deep sleep. This is also the reason you have to press a button to power the system back on again to allow for a new download.
So yes, the problem is related to the official library.
At this point I would not count on the issue being officially resolved anytime soon - the issue has been raised a couple of months ago, the solution is simple, but the M5Stack engineers seem to be busy with new stuff rather than fixing bugs for older hardware.
That said, fortunately the issue can be fixed easily. I suggest you follow the advise in the issue you mentioned and fix the SetSleep() function in your local copy of the M5StackC Plus library yourself.
Good luck!
Felix