Yes I know exactly what problem you are talking about.
It is a rare bug that occurs in the map and it's due to bad creature path finding.
I was going to spend some time trying to make sure it didn't happen, but after a while I just wanted to get the map out already and noticed that the bug doesn't occur very often, so I figured what the hell..
Also I'm not sure exactly what was causing the problem. Everything I tried to change would cause something else not to work right, so I just decided to leave things the way they were and if you watch the cutscene enough times or just have bad luck, you may very well run into the bug, which I believe occurs due to bad path finding on the character's part, not because of any mistakes I made on the map.
To be more specific, I think the reason why it looks like he is standing still and not doing anything is because of a rare bug where the Sylphs stand and shoot him at a constant rate, and since he keeps on getting shot by the Sylphs, he's unable to move due to the constant rate which they shoot him at. The whole time this is occuring, he's really trying to move up to attack one of the Sylphs. Once when I saw the bug come up, the Troll managed to get out of it after 15 seconds and eventually killed the Trolls.
Ah well. It's a hard bug to reproduce, so if you end up seeing it occur, consider yourself having "bad luck" that day.
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Only the
insane equate
pain with success.