2019 Suburban Premier. Sometimes, usually after sitting overnight, the fob/door button only unlocks the drivers side door. Once inside even the door lock/unlock button on the inside will not unlock any of the other doors. I have to manually use the handle from the inside to open the other doors. After driving for awhile, the next time I use the fob/button everything works fine. Took it to dealer several times, showed the tech what was happening, but mechanic could never later duplicate the issue. So they said there’s nothing they can do. I’ve tinkered with all combinations on the center stack for enabling/disabling door lock options, but the issue persists. Any thoughts?

 

I've seen reports of issues in the driver's door lock switch from water intrusion. Drivers' door switch is the master switch.
If it doesn't act up for the tech so the issue can be diagnosed properly, they will not start tossing parts in.

 

For the last 2-3 years I've been always calling local locksmith sw7 every single time I had an issue or another. Frankly, I haven't seen a better locksmith in life. A team of qualified and certified Locksmiths with a huge experience in this field, with pleasant prices for the service.

 

Locksmiths can have crazy high prices. I needed a spare key-fob for my 15' Chevy Malibu. Local locksmith wanted 80 bucks to cut the blade, since the other locksmith in town died. I went to High School with him. Got it cut at Ace for 25 dollars and I only paid Amazon $21 USD for a complete key-fob with a chip and even a new 2032 battery. Go figure!

 

And locksmiths will not open doors up to inspect harness connectors for having water in them either.