The biggest problem with LPG appliances is the gas pressure .
Your oven may need a new thermocouple or most likely it's a heat problem , lpg has a kilowatt rating at 2.75 kpa at the burner .
Low kilowatts reduce the flame temperature , which reduces the millivots of the thermocouple .
Check the regulator pressure it will need to be 3 kpa to compensate for pressure loss ,