Goodbye Automation Not Locking Door

Howdy all. Still new to the way of ST and trying to get everything working as expected. I own a Kwikset 916 lock that works very well with ST, at least manually.

I have the SmartLocks applet from Samsung and mobile presence turned on and they seem to be working surprisingly well, at least for the “I’m Back!” automation. It always sees my wife and/or me and the lock is nicely unlocked for us as we get to the door.

What doesn’t seem to be working is the Goodbye half. Case in point. This morning we both left together in the same car and 20 minutes out we checked the door only to find it never locked. This is now the third time out of three that the door failed to lock with our departure. (for those that might be wondering, I have to manually lock the door to know it worked for the return trip)

What might we be doing wrong here?

Under Settings (gear) I have “Lock these doors” set to the front door lock. Automatically perform “Goodbye!” when… is set to “Everyone Leaves” and "Everyone Leaves is set to both my phone and my wife’s phone under “All of these people”.