This happened to me twice now in my survival world, every thing was ok i was doing a raid and it said that there is one pillager left i started searching for him then suddenly an arrow hits me i stand still and i got shot again and also i could hear him but i couldn't see him i tried many times hitting him and i hit everything around me but i couldn't kill him he was INVISABLE, the second time i was in cave and a punch of zombies attacked me i killed them all but i could still hear one and suddenly i am getting damaged i look around me there is NOTHING i was getting pushed and damaged then i died because bunch of other mobs came to me the zombie was also INVISEBLE i couldn't hit him even tho he was around me somewhere