I know this problem existed before. I encountered it at the time, and your bugfix fixed it for me at the time. However, yesterday I had the problem again where I assigned staff to an expedition and one of my members of staff who (were in the staff only area) just froze instead of leaving on the expedition. I fixed it by removing the staff door and wall it was on. This unlocked the member of staff and they ran for the helicopter.

I don't have a save unfortunately because I just removed the staff door and continued playing. However, in case it helps, the staff door was positioned at the bottom short edge of a 1x4 corridor with a staff room on the left and a training room on the right (the doors to both rooms being opposite one another and at the top of the corridor). Both the staff room and training rooms were the same height as the corridor (4).

This was in Passwater Cove.