End gateways do not work from main island

After killing the Ender Dragon (I've done so multiple times on a survival world with my friend in snapshot 18w46a, then in some solo test worlds in snapshots 18w46a and 18w47b), the main return portal appears and the Dragon drops the experience, as usual. After spotting the end gateway, I build up to it and attempt to throw a pearl through (I've also used an elytra in one instance as a test) and while I get the "Remote Getaway" advancement and I am transported, instead of finding the outer islands, I am teleported back to the starting platform of obsidian (the one you land on when you first enter the End).