This happened on a mission I took before too, from Latos C-2 to Sedina L-2 for Xang Xi. This particular mission was from Sedina L-2 to Sedina K-13, also for Xang Xi. Both times I went ahead (or in this case, to the side) to clear B-8 of pirates. Everytime I do this, the mission stops telling me what's going on, ie the voy si jumping, etc. The first time happened after the convoy had already undocked. This time it happened before they undocked.

[Mon Mar 27 15:52:36 2006] 00ff00Welcome to the group. The mission will begin shortly.
[Mon Mar 27 15:52:38 2006] 00ff00Mission will begin in three minutes.
[Mon Mar 27 15:52:43 2006] 28b4f0[100] <Miles Tails Prowler> Hmph
[Mon Mar 27 15:52:50 2006] 28b4f0[100] <Miles Tails Prowler> a 0 jump mission for escort
[Mon Mar 27 15:53:03 2006] 28b4f0[100] <Miles Tails Prowler> Last one I took of these dissappeared in that single jump
[Mon Mar 27 15:53:08 2006] 00ff00Mission will begin in two minutes, thirty seconds.
[Mon Mar 27 15:53:15 2006] 28b4f0[100] <Miles Tails Prowler> It's like the fucking bermuda triangle
[Mon Mar 27 15:53:25 2006] 28b4f0[100] <Miles Tails Prowler> ...
[Mon Mar 27 15:53:35 2006] 28b4f0[100] <Miles Tails Prowler> In fact, that sounds like a good idea for a new story
[Mon Mar 27 15:53:38 2006] 00ff00Mission will begin in two minutes.
[Mon Mar 27 15:54:11 2006] 00ff00Mission will begin in one minute, thirty seconds.
[Mon Mar 27 15:54:41 2006] 00ff00You are entering Sedina B-8
[Mon Mar 27 15:54:41 2006] 00ff00Mission will begin in one minute.
[Mon Mar 27 15:55:11 2006] 00ff00Mission will begin in thirty seconds.
[Mon Mar 27 15:55:21 2006] 00ff00<Miles Tails Prowler> Oy great guidelady :)
[Mon Mar 27 15:55:27 2006] ffffffMiles Tails Prowler destroyed *Pats Domu
[Mon Mar 27 15:55:27 2006] 00ff00CORVUS is not pleased by the destruction of *Pats Domu.
[Mon Mar 27 15:55:27 2006] 00ff00Combat +400
[Mon Mar 27 15:55:27 2006] 00ff00XANGXI appreciates you dealing with *Pats Domu.
[Mon Mar 27 15:55:27 2006] 00ff001200 credits received
[Mon Mar 27 15:55:27 2006] 00ff00Xang Xi standing increased noticeably
[Mon Mar 27 15:55:30 2006] 00ff00<RelayeR> hi Miles
[Mon Mar 27 15:55:52 2006] ffffffMiles Tails Prowler destroyed *Nebnos Tako
[Mon Mar 27 15:55:52 2006] 00ff00CORVUS is not pleased by the destruction of *Nebnos Tako.
[Mon Mar 27 15:55:52 2006] 00ff00Combat +400
[Mon Mar 27 15:55:52 2006] 00ff00XANGXI appreciates you dealing with *Nebnos Tako.
[Mon Mar 27 15:55:52 2006] 00ff001200 credits received
[Mon Mar 27 15:55:52 2006] 00ff00Xang Xi standing increased noticeably
[Mon Mar 27 15:56:10 2006] 00ff00<RelayeR> hi Root
[Mon Mar 27 15:56:28 2006] 00ffff*Krotka Rastrasen warped to Latos System, Sector O-12
[Mon Mar 27 15:56:35 2006] 00ff00You are entering Latos O-12
[Mon Mar 27 15:56:39 2006] 28b4f0[100] <Miles Tails Prowler> Oooooooh, so that's why missions cancel on me
[Mon Mar 27 15:56:49 2006] 28b4f0[100] <Miles Tails Prowler> If I kill a corvus bot before it begins
[Mon Mar 27 15:57:08 2006] ffffffMiles Tails Prowler destroyed *Krotka Rastrasen
[Mon Mar 27 15:57:08 2006] 00ff00CORVUS is not pleased by the destruction of *Krotka Rastrasen.
[Mon Mar 27 15:57:08 2006] 00ff00Combat +400
[Mon Mar 27 15:57:08 2006] 00ff00XANGXI appreciates you dealing with *Krotka Rastrasen.
[Mon Mar 27 15:57:08 2006] 00ff001200 credits received
[Mon Mar 27 15:57:08 2006] 00ff00Xang Xi standing increased noticeably

Identical situation happened to me on Sunday. Reported using the /mission bug tool. I've done other escort missions and killed Corvus bots before the convoy undocked without triggering this bug though.

Maybe it's missions to the same faction that go bonkers. Had one like that between the two tung stations.

And my convoy only seemed to consist of defenders.

I've made some major changes to the Escort mission and Deliverator missions in general. I'm still ironing the last of the kinks out with this, but I expect it to make bugs like this a thing of the past. <knocks on wood> That will be out later this week with any luck.

Thankee, moemrath. Keep up the good work :D