I was building a rainbow beacon tower leaving an Armour Stand wave machine on.(it caused lag but I just ignored.) Since I haven't slept for nearly 2 hrs, more than a dozen of phantoms spawned but i ignored.(Do phantoms spawn this much?)

Then i realised that sth went wrong. All of the phantoms(except the newly spawned) stopped moving, even when they were damaged. 

Is it because of lag?

And, why are that armour stands staying still?