Alien pq glitched?

Corsair - Bullseye/Homing Beacon
Evan - Killer Wings

Not too sure about Killer Wings, but Bullseye/Homing has disconnected people (in Energy Cube from my experience). They use similar if not the same mechanics

Blade Master - Monster Bomb, I believe this causes DC also.

General rule though, I'd say avoid using any skill with special mechanics, such as "Lock-on" on Homing/Bullseye or "OHKO" from Snipe.

DoT damage such as burn or poison are fine.

I run regularly with MMs and they have never DC'd from using Snipe.