I've deleted the M8 and M3B Rearguard jobs from XRM Jobs after finding a Split Rearguard M8 Patrol, Boron Rearguard M8 Patrol, and Argon Rearguard M8 Patrol all in Ringo Moon.
I don't know why they haven't been working as intended (as the M3Bs seem fine), but they're more trouble than they're worth, and I know a few of you don't like them anyhow.
Paul's never seen them fire missile, so IDK WTH.

To compensate, I've upped each Race's M6/TM patrol count by 2 (from 10 to 12) and given the lead ship the chance to spawn as an M8, so they're M6/M8/TM patrols now.
Expect them in the next micro-update.
Since I've deleted them, it'll mean that they'll show up as blank-name jobs in existing games, so you should be able to totally remove them from your game with that "remove blank name ships" script.