It goes out when I let go

It lights, then goes out when I let go of the knob

The flame safety device shuts the gas when it does not sense the flame. Ooni's fixes, in order (Essentials Guide; help centre):

• Hold the knob in for 5 seconds after it lights, or 20 seconds when relighting after a flame-out.
• Shelter the oven from the wind.
• US: reset the regulator (see it will not light).
• Wipe the thermocouple with dry paper towel, or blow it clean, oven cold.
• If it keeps cutting out, tighten the flame safety nut inside the burner housing with an 8 mm spanner.