Q: Stalls intermittently when making left/pushing down on turn signal

My wife drives a 2016 GMC Terrain Denali. It has about 12000 miles on it. Intermittently when she is pushes down on the left turn signal the vehicle stalls. The car goes completely dead. Dash lights and everything she says turns off. The problem is so intermittent that sometimes it may happen once a month and then go a couple of months without doing it.

I have asked my wife what other variables exist when this happens and she could only recall the radio being on when this occurs.

My wife is getting scared to drive this car. This is our third GMC and we love them.

We have taken it back to our GMC dealer several times. They are trying hard to duplicate the issue but no luck yet.

My car has 12000 miles.
My car has an automatic transmission.