Dometic refrigerator

Put a screen on the inside of the exterior air vent. Stops/reduces draft putting pilot light out.

I had it happen to me a few years back.
Check your 12 volt when plugged in to see if you get around 13 volts. If the converter is shot, the fridge will shut down when it looses a small amount of DC voltage. It would run as long a the tow vehicle was supplying the 12 volt.

Don't think it is an altitude problem. Went up to about 4500 ft is all.

I have had issues with altitude, don't know if that is the issue with the OP. When traveling above 7000 ft or so, below that not an issue what so ever. I will lose the flame and need to restart. I have cleaned, changed jets, and etc and still issues. I inquired with Dometic and they did indicate that above a certain altitude there may be issues. When that starts to happen, I just keep the door closed and move on. Usually when I stop, I restart the flame and its fine till I start moving again. We just deal with it. Really never a big issue.

might clean the burner, I was having a problem with mine ,cleaned burner works great , its not a hard job, I also cleaner my flue pipe.

Check light is on due to flame failure.

No pilot flame.

Electronic ignition lights main flame as needed for cooling cycle.

If it fails to light and 'prove' that it is lit circuit board shuts gas valve
Control circuit will make 3 attempts to light/prove flame then lock attempts out and trigger fault (Check light)

Could be due to air currents (rare on a 5th wheel)
Could be due to dirty burner
Could be due to dirty spark electrode
Could be due to spark electrode being out of position (needs to be engulfed/remain engulfed in main flame)