How to force end gateways to regenerate in minecraft?
Solution 1:
So I figured out the solution to the problem. First it is important to note that the teleportation data is stored in block data. Secondly, when in the end, an end portal without block data defaults to its spawning state.
The way to fix the problem is to respawn all end gateway blocks via the set block command. Example for gateway 17:
/setblock 29 75 -91 minecraft:end_gateway 0
This will respawn that particular gateway and everything will run smoothly from there.