mobs despawn when nametagged on realms. COMPLETELLY VANILLA

after searching online this appears to be a known issue going on for approximately three years now with 0 fix I could find. it is literally only in realms. doesnt matter if zombies are nametagged, in boats, holding something or spawned in with commands. they will despawn. there is 0 mods, 0 datapacks, 0 plugins. 100% vanilla realm.