I have seen the cruddy Drengin Super Dominator Corvettes go invisible in the latest build. Three attacked an Arcean ship, and one was destroyed. The remainder of the fleet actually went invisible during the battle. I was watching from zoom level 2.
Yeah, unfortunately I've noticed it again as well. Lots and lots of them. I still can't figure out why they build so many even when they obviously have better designs (all the other ones that aren't invisible). I guess they are building them early in the game and then just holding on to them for cannon fodder.