Placed Shulker Boxes Disappeared When Switching Dimensions?

I have been working in the End, and I was transferring and placing shulker boxes from the Overworld to the End. I placed 5 shulker boxes (and a crafting table), all completely full, in the End, and came back to find that they were all gone. I've checked anywhere they could've possibly been, but to no avail. I gone was at most maybe 2 minutes, so it is highly unlikely that endermen could've taken all 5 shulker boxes (if they can even pick them up) and the crafting table and transported them somewhere else. I also thoroughly checked the End island and did not find the missing boxes or crafting table. What happened here?

edit: The shulker boxes were placed on this obsidian in the room.