2003 rear passenger door lock issue - intermittent

[treat44]

I did a search and couldn't find anything specific to the pattern I've found.
One day, my rear passenger door lock quit working with the doors locked using central unlock method. The child safety locks were ON, so I wasn't able to unlock via interior handle method. Door inoperable.

Fast forward a few weeks. The door begins working normal again. I turned child safety lock OFF immediately.
Fast forward a few weeks. The interior handle would no longer unlock door (child safety still OFF).
Fast forward a few more weeks. The door works normally.

Now that I can open the door, I'd like to address this intermittent issue. I think I found a pattern. Lock door, doesn't matter if I push manually on lock rod or use central locking system...unlock doors, again, method doesn't matter. Door will not open from inside UNLESS I use exterior handle first. Wierd thing is, first exterior handle pull does nothing. Second exterior handle pull opens door perfectly with no evidence of mechanical binding. I am wondering if the first exterior door pull actually is doing the unlocking of the door latch. What doesn't make sense here, however, is that the first INTERIOR handle pull physically raises door lock rod. Second interior handle pull doesn't seem to open door...unless the exterior handle is pulled at least once first.

I'm thinking door latch assy.....thoughts?
Definately doesn't seem to be a mechanical issue, as interior handle pulls activates lock rod to move upward and exterior handle pulls eventually open door fine after pulled twice.