I have the same one (I think) - direct spark ignition, no pilot light. Haven't had an issue with start-up on gas. After the main LPG shut off has been closed for a while, I alway light one of the the stove-top burners as a way of getting most of the air out of the system. I've never had a problem with the WH not firing up when required.
If the igniter is clicking but the burner isn't lighting off, you have either a gas supply problem or some foreign objects in the burner system tubing (spider nests, other bugs).
Frank and Eileen
No longer RVers or FR owners