In the mission to destroy the hidden Ares fleet (first Point Juno mission), the Sandstorms protecting the Chasm that's the mission target made no response whatsoever as I tore them apart. Completely passive until the Chasm died.
Similarly, after destroying the Chasm and being informed that Point Juno was under attack, I flew back only to discover that Point Juno's guards had flown off to attack the other fleet, which was slowly flying towards Point Juno and making no action to protect themselves from said guards.
Because they ordered to escort with fleet command. As long Chasm not ordered to attack something, they will stay in formation.
Yes, the Chasm and escorts just sit there. I've seen this multiple times. They do eventually take off but not for a long time. The surrounding sentries fire on the player as normal.
And the Tundra and escorts are 'attacking in formation'. It will swoop in and attack then retreat backwards, then do it all over again. Kill the Tundra and it becomes a free for all.
The problem is that if you intercept the Tundra's fleet before it gets to the station, then it makes zero effort to protect itself. In such a situation the fleet should decide it has to deal with the station guards before attacking the station itself.
As for the Chasm's fleet, there I'd probably just make it so that the entire fleet does "break and attack" as soon as the player gets close or any ship in the fleet is destroyed.
Fixed in 1.9 Beta 4. Now the fleets react to attack.