The 4th mission is entirely RNG who you get. I find the composition with a bunch of AoE clones and the fish Jedi to be much harder than some of the others. With my mods I can't possibly keep them all ability blocked. Mostly I get hit with an AoE that kills 1-3 bugs from nearly full. This last time I got hit with an AoE Daze which pretty much shuts down the only strength of the team.
When I got a different comp for round 4, I beat it easily with bugs that were lower geared and worse modded than what I have now.