Lennox furnace not working pilot light on but burner doesn’t start

Sounds like you have most of the common bases covered. This happened to me and it was the blocked inlet valve, a leaf had gotten sucked in. It took me a while to find it, it was not in the visible area of the inlet, it was stuck on a screen to catch debris. I would double check that. Maybe try to blow some air in the inlet from the outside of the house and see if you feel the movement in the furnace.

This question is similar and may have some other suggestions.

Gas appliances tend to use a thermocouple (which is a self-powering device) to keep the gas valve to the pilot light open. This means that the light will not go out when you turn off the breaker. Thermocouples are pretty interesting - learn more on Wikipedia here.