Passenger Rear Door will not open!

So our '07 ESV ended up with a broken exterior rear handle. "Fine" I thought to myself ... Especially as the child lock was on, which proved to be a complete bitch to get the interior trim off without breaking it and opening the door from inside the door.
Ordered a new replacement from rock-auto for 60 bucks, fitted it, tested the door numerous times (open/close) and all was well...
I left the interior trim off until the next day wanting to make doubly sure that all was fine with the new handle.
The next day ... My wife tried to open the door and it wouldn't open ... Thought she was jiving me around but nope, sure enough, the door was screwed again!
So after another hour in the garage to investigate why the door will not open ...
After locking the car with the keyfob, the door appears to unlock, yet the exterior handle refuses to open the door ... Including the interior handle for that matter!!!!!
Crawled in the back again and fiddled with the lock inside the door until it popped open ... Tested numerous times "again" (open/close) and all fine all until the car gets locked the door refuses to open again!!! Trying to avoid a trip to the dealers for hopefully a simple fix ...

Has anyone else experienced this phenomenon?

Does anyone have a solution to what I have described??

Thanks!
Russell