Move to Safety "To Do" item

When a dupe gets the "Move self to safety" task, sometimes strange things happen.  The task shows up as a priority of -1, and blocks all other tasks from happening.  However, the dupe appears to get stuck while on this task.  The first time this happened, a dupe was drowning and went into panic mode and wouldn't climb up the ladder even though he was two cells from safety.  The second time it happened, Frankie got into a loop of hopping between the ladder and the fire escape pole without actually going anywhere.  Fortunately that time he was in a mostly-oxygen area and once he caught his breath, he went on to other things.

I keep forgetting to save while the dupe is stuck, so I don't have an example. Both times my dupes have survived, but in the first case I had to manually move him to safety before he drowned.  

Unfortunately, this doesn't happen every time, so it isn't predictable.  Most times they'll behave properly and move themselves to safety.  I haven't been able to figure out the precise cause yet.  If I can get a save where its happening, I'll post it.