More Detailed Visual Description In The Attachments below:
Description: I was trying to make a boss on realms and had it rigged to machine to summon lightning on zombies nearby, and it worked. I left the game and it left its team.
Steps to replicate:
1. Do this command:
/summon villager ~ ~1 ~ {CustomName:"TESTIFICATE",CustomNameVisible:1,Tags:["cool"],Profession:5,Age:9000.1,ForcedAge:9000.1,ArmorItems:[{},{},{},

],ArmorDropChances:[0.085F,0.085F,0.085F,0.0F],PersistenceRequired:1,CanPickUpLoot:1b,Silent:1,Glowing:1b,Team:"TESTIFICATE"}
2. Hook the mob up with a machine with the following command:
/execute @e[tag=cool] ~ ~ ~ /execute @e[type=zombie,r=100] ~ ~ ~ /summon lightning_bolt ~ ~ ~
3. I placed zombies.
4. Left game.
5. Came back on and it left its team.