[1.3.3389 (64-bit)] mechanoid raid didn't trigger completion properly

[tswaters]

Basically As the subject says, got a mech drop, defeated it and the game doesn't recognize it's been defeated so I can't destroy the buildings.

I did see this: https://ludeon.com/forums/index.php?topic=50468.msg471119 but this isn't a quest, it was just a mech cluster drop so I'm unable to follow the instructions.  Quest pane doesn't show any mech drops (even with "dev: show all" checked)

Here's the save file:  https://drive.google.com/file/d/1hTSsMp53T3Ij3E162EknOSFj7L_SWbpK/view?usp=sharing

I'm in the midst of a quest to defeat a ton of tribals with the help of some troopers.  The first raid has gone off (see ~50 bodies in south of map, was a series of mortar attacks -- each wave is ~130 tribals) -- in the midst of that, had a couple of mech drops.  First one went off without a hitch, second one gets into this state.

Wild speculation:  This dropped on my devilstrand plot which I haven't seen before.  Also the size was a lot smaller than drops I've seen in the past, only like 2 centipedes and like 5/6 each of the sythers/lancers.  Maybe some of the mechs didn't spawn properly and the game thinks there's mobs that need to get defeated that never spawned?   Not sure.

[tswaters]

So I'm a dumbass, but I destroyed the mech assembler building and it gave me "mech cluster defeated"