: The first time, I let an enemy Marine board first. There was no prompt for me
: any more, and his AR fired bullets my way despite pointing a very
: different way. The Pelican just hovered. Maybe if I'd waited long enough
: to be forgiven, the prompt would've reappeared? The second time, I boarded
: before the one remaining enemy Marine, and got flown off alone.

: Are you sure all the covies had been killed? I'm just wondering if you had
: one lurking in the rockslide, in which case the Pelican wouldn't have
: triggered.

I've experienced this three time before. It turned out I had one grunt left on the map, and that red enemy marker didn't display as usual, I sent a few minutes hunting down and killing the last remaining grunt. After that I was able to board the Pelican and proceed to the next mission. The game needs a new bug/glitch fix.