I usually purge the air out of gas line by lighting the burners on stove. Then I make sure the frig will light off on propane. The frig will fail to light now and then until all the air is out of line.
Just working from memory here, but I think if the frig fails to start after a few igniter tries, you need to slide to Off and then back to Auto to reset the starting cycle. I think the light on the selector flashes on a failed start. Mine usually starts on the second try. I also leave it on Auto when traveling unless entering an area that prohibits leaving it on.
2015 Thor Vegas 24.1 in Ocala