Cannot summon an entity with a custom UUID

Hi,

I wanted to summon an entity with a custom UUID to combine with the "ownerName" in some projectiles.

But it seems that it's not possible anymore:

    /scoreboard objectives add test dummy
    /scoreboard objectives setdisplay sidebar test
    /summon ArmorStand 275 56 920 {UUID:"8ed0f252-5fea-41e6-9189-75915fb00b9c"}
    /scoreboard players set @e[type=ArmorStand] test 1

And each time I have a different UUID displayed but never the one I specified.

• This UUID is one that the ArmorStand once took
• There's only me and this ArmorStand in this world (no other entities) and my UUID is not that one
• Even with "2-2-2-2-2" as UUID the problem is the same. It worked back in some previous snapshot (in summon and in ownerName) but not anymore.

Thanks

Korko