I've been driving myself crazy the last couple days trying to get my mannequins and bookcases to work. Even though they were set up exactly the same way, some mannequins and bookshelves worked great and with others the activators wouldn't show up in game for the player to interact with. Finally I noticed that the only mannequins and bookcases that weren't working were those facing north (orientation 0,0,0 in the cell, I call that north for some arbitrary reason). So I rotated the bookshelf activators 1 degree and they started working. The mannequins needed to be oriented about 45 degrees or more to become responsive.

I'd be curious if someone else would be able to duplicate this, and if I'm right, I hope it solves some of the frustrations people have been having with this.

Just spent the last hour testing the heck out of this and con confirm that if the mannequin itself is facing north (0, 0, 0) then it will not function. However if I rotated the mannequin and activator off north by 45 deg. but left the heading marker facing north then in-game the mannequin would face north and function if a little buggy unless you approach from off to the side a bit. Going to try just rotating the activator to see if that works better.

Edit: Okay just checked again if you leave both the mannequin and heading marker facing north but rotate the activator by 45 degrees then everything seems to work perfectly without any issues at all. I just had to enlarge the activator a little bit to keep the whole mannequin inside at the 45 degree angle.

It's 90 or -90 degree z rotations on pretty much any of the activators...weapon racks, plaques, bookshelves, etc. If you alter them by 1 degree + or - they will work. Weird huh?

I spent a few hours on this a couple weeks ago trying to figure it out. Been trying to spread the word since.

There is already a lot of post about that. And you can expand the trigger a litlle on mannequin, activate the collision geometry in the view menu, and make the trigger to be a little more big than the collision geometry of the mannequin in the front side.