Invisible mobs

ANyone else finding invisible mobs in the void?
I started a new hero in hardcore mode and one of the mob types (unfortunately I cant recall its name but its the largest one that jumps, lands on you and sends out fire damage in 3 directions) is invisible 100% of the time. You can see its spell effects and your spell effects when you hit it but other than that you have no idea where it is until it gives itself away.
LOL
its one way to make the game harder.

It’s either that or they are under the floor.

Try verifying your Steam files integrity. Sometimes a corrupt texture file can be the cause.