Does the door button inside work correctly?
You should have two relays according to the service manual, I believe they are imbedded in the door.
My molten 11+ has the twice unlocked. If I blade one or fob unlock one it's drivers only. That uses relay one and arms relay two. A second press uses relay two and resets all to standby. There are a few hidden fuses. For example, one carrier in the box by the steering wheel holds two fuses.
You could also try reprogramming for all/all. I have not tried this, but it's something to consider.

you can easy adjust it so that it will open all the doors at one push of the button instead of two, its all explained in your owners manual.
"you can change the system to unlock all doors by one pressing the unlock button....press the lock button and unlock button at the same time for 5 seconds or more. The hazard warning lights will blink four times

 

Any ideas on what Kia would charge to diagnose problem?

(teasing) About as much as you paid for the car.
Seriously though, the only reasonable estimate would be to call your local dealer and ask for the service mgr. Ask them about diagnostic charges, if they will apply them to the repairs and make sure to get things in writing. All of the shops I've ever dealt with would say essentially "I don't know what is wrong with it anymore than you do" "I'll take a look and charge you $$$$$ per hour."
Both of the repair facilities I worked for as a mechanic would apply diagnostic charges to repair labor at the time on the spot. ( we've already got it apart and know what to replace, just say the word and we'll swap parts)

 

Stopped by nearby dealer today. He quoted $85 to diagnose door lock problem, said he would credit toward repair. I am very cautious as I had a somewhat similar problem with my Toyota Highlander that turned into a real fiasco. So I'll risk the $85 and see what happens.

 

I have the exact same problem, preety sure ita the door actuator, pls let us know whet the problem is.