My biggest problem in catching Goblins has actually been that my military likes to just wander randomly, often outside of the fort walls for no good reason. There's no meeting zones out there, and the outdoors meeting zone is well away from the outer walls, so I can only assume they do it to piss me off. Animals seem to do that a lot too. The last ambush, some idiot dear fawn wandered outside and revealed the ambush, so I figured I'd have minus one idiot deer and plus 12 Gobbos. Instead, one of my military's champions decided that this was a fine time to go commune with nature and started to head outside. In desperation, I activated his squad and set his patrol route well away from outdoors, but to no avail. Only 4 Gobbos survived long enough to get caught. I have the weirdest luck ever, I swear...
This is a major and EXTREMELY frustrating bug I'm noticing in several areas.
I think that with the way rooms are defined now, there is a bug where the walls are included as "tiles" inside rooms, but when a dwarf wants to stand on that tile, and finds it blocked, they will then try to stand on an adjacent tile, instead.
Thanks to a lack of sanity checks, this will cause dwarves to actually think that the closest tile to the one they want to stand in is OUTSIDE YOUR FORT, and will rush outside to conduct meetings with people who are inside even when outside is forbidden, it is several hundred steps away when they were already INSIDE THE ROOM, or anything else.
For some odd reason, once this has started, they MUST stand in their pathed-to tile, they don't stop even when you activate and deactivate them. The only thing that stops them is locking a door in front of them, watching them slam face-first into it, then hoping that they re-path to something sane, or that you have given them over-riding commands.
For that reason, doors are like dakka, you never have enough doors. One of the things I'm learning is that doors are a solution to almost any problem, INCLUDING magma.