wel this is familiar like other stuff like in modded things just save quit and than start up the world again if it takes to long same with in a server this methode worked fine for me but hope it gets fixed (sometimes its disturbing) and i used the chuck option on 6 to 8
same over here but also in difficulty hard i had to spawn in the dragon with the clay block creeper face but than the health bar of the dragon wont show up on the screen
i made a end portal in creative wile mi difficulty was on Hard and entered the end portal wile in creative andthe dragon didnt spawn
edit: but in a second test world i made the dragon did spawn but than the difficulty was on normal and i was also in creative
yep have it to but its not backwards by me the head isnt showing by me
maybe the amount of lagg form entities in the chucks around your spawn area in the server