When I was using commands I could not make entities besides armor stands become invisible. I was using this command. I don't know if its the command or what.
/summon minecraft:shulker 358 64 298

{NoGravity:1,Invulnerable:1,Invisible:1,DisabledSlots:2039552,NoAI:1}

and also this.

/summon minecraft:shulker 358 64 298

{NoAI:1,Invisible:1}