Can't place End portal block in the End using commands

If you try to place end portal, the portal isn't placed. Instead, the block is air.

How to reproduce :
Do one of the commands:

/fill ~-1 ~-1 ~-1 ~1 ~-1 ~1 end_portal
/setblock ~ ~-1 ~ end_portal

EDIT : If you place manually the portal block, the portal despawn.