Refrigerator wont stay lit

I just bought a low mileage 2014 Navion 24J with Norcold refrig. The fridge is part of the slide-out and works great on electric and gas . When I switch to gas, it works great until I extend the slide- out, then both lights blink. I can extend slide to about 1/2 way before it quits, anything more and it won’t light. Any ideas ? I’m not sure if this is related but the propane seems to drop quickly to 1/4 tank from full with only a few days of usage using only the fridge and just a little hot water, maybe one or two quick showers. When I brought it in for a fillup, one place couldn’t get any gas in at all so I went to the dealer and he put in only 2 or 3 gallons and it was full. This rig was used very little and I’m wondering if the tank wasn’t purged when new. Not sure why this would affect the fridge when the slider is out but I’m baffled. All other appliances work fine at 1/4 tank so I don’t think it’s a low fuel issue because it works fine when the slider is in. Thanks for any advice!