Just had the same thing happen, you could hear the gas valve open, hear the spark, smell raw gas at exhaust.
Removed the burner, real easy 4 screws, the wire to the valve, and gas connection. Found the burner grate rusted over, wired brushed and all is good again.
2009 Monaco Monarch 33SFS...Jeep TJ
Wintering in Apache Junction. Summer in Ontario.