Not making any sense. You should have 120vac at timer BU terminal. Input to timer is at BK terminal. You should have 120vac there. Power goes through timer contact to PK terminal and through another contact to BU terminal. You should have 120vac at each with timer on. Maybe your not getting good ground with meter probe. Use neutral instead at timer RD terminal. Exhaust temp is too low. The cycling thermostat won't switch until temp gets to 150°. Voltage at OR is to be checked when burner cycles off via switching of cycling thermostat, not just when burner off. i.e., temp must get over 150° to make cycling thermostat switch. At that point, power is directed to timer motor vice ignitor and gas coils.

Eric

Notice that the OR terminal on timer has an orange wire that comes from the cycling thermostat and a wire to the timer motor. When cycling thermostat cycles the burner off it applies 120vac to orange wire which you say you are getting at OR terminal. That means you have 120vac across timer motor. Timer motor should be advancing timer. When cycling thermostat cycles burner back on, power is removed from orange wire and timer will stop. At end of auto-dry cycle power is applied to timer motor continuously via internal timer contact so timer will advance regardless of cycling thermostat. Don't know what else to suggest. If burner is cycling properly, and your seeing that at timer OR terminal, but timer won't advance, then perhaps the timer is faulty.

Eric

Why not just use the timed dry function of the timer? The heat still cycles to maintain proper temperature. The only difference is that in timed dry, the timer runs continuously til end of cycle. Remember, if you buy the timer from APP and it doesn't fix the problem, you may return it.

Whirlpool 33001631 Timer - AppliancePartsPros.com

Eric