I had spawned in two Illager's  and five Pillager's using a dispenser. To my surprise I was killed shortly after, upon respawning I was killed again but this time there were no visible mobs. I had realized the mobs were invisible when I noticed arrows flying past my head. This was not a major issue as it was in a snapshot world. I feel this issue would be very aggravating in an actual world, such as a single player or multi player world.