I think what you have is a problem with the sensors at the door. Each of them should have a small light. If one is lit and the other is not it is probably misalignment. They must be pointed at one another to work correctly. Tweak them a bit and see if you can get both lights on.

Both of the lights are on, they're both green. So they seem to be aligned okay

It is important that you look very closely at those green lights to make sure one is not blinking ever so slightly. It seems dumb but there are occasions where the sensor is receiving enough of the infrared signal to turn the light on but not enough to satisfy the logic board. You haven't mentioned if the main light on the motor unit flashes 10 times. If it does it verifies misaligned sensors.