I tried to change my settings when I first joined a server.
After getting back into the game, it said I was unconscious.
I waited for like 2 minutes and kind of got a little impatient and clicked Restart.
I think, I restarted my whole game after that and logged back in.
Since then I can't die, neither by falldamage, neither by player or zombies or anything.
Also I drop tons amount of blood and my screen is all grey
EDIT: Also the "Restart" button isn't clickable (grey)
Are you still in this state? If so please can you give me your player name
If not are you able to reproduce this issue again if so how?
Luckily in the End, after running around for an hour or so I was finally able to die by falldamage.
I tried to reproduce it, but never ended up unconscious after changing any settings.
Thanks for the help though :)
EDIT:
I forgot to mention, that dying by falldamage only worked after the massive bleeding has stopped, I hope that this information may help.