Mobs Can't Join Teams?

Normally, you can summon a mob with an nbt that makes it join a team as soon as it spawns. However, this doesn't work in my server while it does work in singleplayer. And even if I force the mob to join a team afterwards, it doesn't exhibit behaviors mobs normally go through when in a team (mobs don't attack players in the same team as them). Is this a bug, or is what I want just not possible?

In singleplayer, mobs do not target players in the same team as them. Try it for yourself., cause I've tested it. In the server, it's not the same.

Just tried it, it works fine in vanilla. Must be something with Papermc.

<Edit>: I downloaded CraftBukkit for my server and the mobs behave fine, so the problem might be exclusive to paper