Furnace won't fire alone

[Rhider]

2011 Alpine with heat pump.

We have been using the heat pump along with electric fireplace as our heat source. We couldn't get the furnace to fire. It would attempt 3 times then shut off.

Today waking up to 23° in North Carolina the furnace was running while thermostat was in HP mode. I have researched this is normal when the temps outside drop it will switch between HP and furnace. It seems to cycle every 2-3 minutes between the two heat sources.

So excited to find the furnace actually works i changed thermostat to FURN and nothing... so here's the question.

Why would the furnace work to supplement the heat pump but not when T-stat is set to FURN?

[jsb5717]

If the furnace actually fires and produces heat as it should then I would definitely look at the thermostat. Can you post a pic of it? Regardless, I would look there as the culprit.