I was playing my hardcore world earlier and beating the ender dragon 20 times to open up all end gate ways when I put my end crystal at the portal to the overworld to spawn the dragon and whilst the end crystal was generating in the obsidian towers I saved and quit my game just to grab snacks and when I got back it was stuck at the last obsidian tower that was generating the crystal. It didn't move to another obsidian tower but it was stuck at the tower which was the last tower that generated before I logged off. The bad thing is when I shot the main end crystal that was at the portal to the overworld it didn't open. I recreated this in a creative world just to see and it happened still. Here are the result from my creative. I hope this get fixed soon because now I need to start a brand new survival and not hardcore anymore haha. 

The first pic is when I put the end crystal
The second pic is when I saved and quit
The third is where you can see it gets stuck at the end crystal of the tower 
The fourt pic is when I shot the main crystal at the bedrock frame
Fifth pic is you can see that the end crystal at the tower and the portal is nowhere to be found. I hope this get fixed soon because it is bad.
I am playing vanilla 1.16.2
*Edit- This still is in 1.16.3 rc 1 and I have screeenshot of both 1.16.2 and 1.16.3-rc 1. The screenshot of rc 1 is just the same scenario of 1.16.2
Had to repost this because I was just getting ignored and this is bad for hardcore players. Real sorry if I posted to I hope it gets fixed soon in 1.16.3