/summon thrownpotion despawns instantly

I used this command in a command block
summon ThrownPotion ~ ~4 ~ {Potion:{Id:373,Damage:16417,Count:1,tag:{CustomPotionEffects:[

{Id:1,Amplifier:1,Duration:11}

]}}}

Object summoned successfully

The potion spawns in the prescribed space above the command block, then vanishes 1 tick later. It does not collide with any physical block, nor does it's effect activate. The item despawns too fast to tell if its velocity is frozen or not.