Please keep us posted. I have had the same EXACT issue. Went through it with Trane's light commercial tech support and they couldn't give me an answer. I changed the board as suggested and still..................no luck. Tech support had me disable the economizer, options, and ignition modules which he claims could cause a similar issue. My unit was a heat pump, and it acted as if circuit 1 didn't exist. It would completely skip over all of the circuit 1 test functions. Definitely logic related, not safeties or contactors.
To this day 1 year later, the customer luckily has not complained about it. By the way if it matters this unit is on a Trane stat not sure about yours.
I had a similar problem and turns out that the board was sending 24v to both sides of the C1 coil. When I would test each side of the coil to ground I would get 24v so it wouldn't pull in obviously. There was an identical unit next to it, swapped boards and it worked out, ordered a new board, installed it and it runs like a top now.
"You better watch who you're calling a child Lois. Because if I'm a child then you know what that makes you? A pedophile, and I'll be damned if I'm gonna stand here and be lectured by a pervert."
Have you checked the reading of the OAT? Ive had several sensors fail and hold out the first stage. Disconnect the sensor and it reads a default 74. I had a bunch reading -10 outside when it was in the 90's. I have a Trane manual with all the sensor readings in my van. You can email me if needed and tell me what the DCV readings are and I can tell you if its within range.