I tried it again with my burst altitude set a bit higher (2500 instead of default 1800), and this time I killed all four mortars and both trucks, but the mission did not proceed, I still got the comms regarding the wingman attacking, and he still circled endlessly.
This is the second mission out of 4 where I have encountered mission-breaking bugs. In the previous mission I had a situation where after destroying the convoy, the radio conversation just stopped abruptly in the middle before the next target was assigned, and after that nothing ever happened. I retried the mission and it happened again, then again and finally got it to proceed.
I think I may need to take a break from this campaign until it gets some more fixes.
EDIT: Which is a shame, because other than the bugs and random DCS crashes, I'm really enjoying it.
EDIT 2: Also, for what it's worth, I have zero mods installed, and disabled all data export things like Tacview, except the export to my WinWing ICP panel.