invisible mobs

hello.   

Me and my friend play in a realm together and we all have been getting attacked by invisible mobs out of nowhere. We where in the nether in a warped fungus biome and I was killed by an invisible enderman. Before that I was attacked by an invisible skeleton and an invisible zombie at one time. We still continue to run into these invisible mobs. this is very strange and I hope you can fix it. I cant include a screenshot because the mobs are invisible.