Unable to /fill ... end_gateway 0 replace wool 11

I think the new end gateways look cool, but since you cannot place them manually, I attempted to set up a fill clock with this command:

`execute ajthemacboy ~ ~ ~ fill ~-5 ~-5 ~-5 ~5 ~5 ~5 end_gateway 0 replace wool 11`

So every time I placed a blue wool block, it would be replaced by an end gateway. However, it simply doesn't work; the command block says 'Failed to execute' and when I try the command in chat, I get this:

`[Client thread/INFO]: [CHAT] Data tag parsing failed: Invalid tag encountered, expected '{' as first char.`

I believe this to be because of added support for NBT data in block commands, but since the help menu for /fill still doesn't include its usage, this is a bug.