I've have seen this now several times and each time I'm close to crying out of frustration and confusion.

 

Situation: I position my party at a choke point, then send my rogue out to set some traps and maybe even one-hit a weaker enemy to lure the mob to us. The rogue does her stuff, combat initiates, the enemy comes a-rolling, and then...MY ROGUE IS BLOCKED. Nobody in the party has moved an inch, the rogue could leave the choke just fine, but re-entering seems to be a problem all of the sudden.

 

Result: Rogue stands in the way of my front line melees who can't do anything until she's downed. Bummer.

 

Can anyone explain this to me?

Maybe the combat engagement area is larger and/or more critically defined than the non-combat area for movement purposes.

Yes, I've noticed that and it sucks. Whenever it's a bug or a feature, I hope Obsidian changes it.

Could be, and that would really something that screws up pre-combat positioning and tactics, much in the way I described, but possibly in other situations as well. :/

One solution to your current scenario would be to have your rogue use that "shadowed" talent that makes them invisible after setting traps and/or one shotting someone and move them away from the enemies leaving the enemy a clear path to your tanks before attacking them from the rear?

Thanks, but I'm not wasting talent slots for workaround like that. I'll just have to take extra care to leave a corridor until the rogue is back and then manually close the gap with my melees. I remember BG2 having a 'let through' gimmick for this kind of thing, but I'm not sure if it was out-of-combat only as well.