a custom end portal in snapshot occasionally spans me to a void

occasionally when i go through a custom end portal, I spawn in a completely black location similar to the void, but i cannot jump or fly away in creative, or anything. to escape i had to type in the the kill command.
It could possibly only occur when i fly into the portal in creative mode, but occurs every other time I hop inside.

-UPDATE definitely only occurs when I fly into the portal. To repeat: be in creative mode, create end portal, hover over end portal, enter the portal by using sneak button to fly down into portal. upon re-entering the portal the correct way, my belongings are scattered near my location from my death.