gravity blocks falling through the end portal don't show up in the end

So i tried to make the gravity block duper shulkercraft made, it all got done, but when activating it, it doesn't drop any blocks in the end, even placing them manually didn't work, then i tested it on another server which has no bukkit/spigot, then it worked, is it a setting what i can't find or is it unchangeable and comes with paper?