I have the same issue.
Version 1.17.11 Windows 10 edition played on a REALM.
The first few times it worked, then suddenly not anymore. We are two players on the REALM.
I also downloaded the world to see if it makes any differences to play it locally. But no chance.
So when I use the End Gateway on the main island, it does teleport me to the main island just next to the Over-world portal.
When I fly out to the outer area and use there a end gateway, I do end up at the main island under the End Gateway (I have tested this with several end gateways in the outer areas and it always works). So the way back is working. but not from the main island to the outer area.
I have the same issue on my Realm. Not only with name tacs but also with any other item. I normally rename something (e.g. bamboo) for the item sorter, so that I can use these renamed items and be sure that they stay in the hoppers.
I then downloaded the world and did try it locally and there it works.
I use Minecraft Bedrock 1.17.34 on a Win10 PC