Millis() not working

[camsysca]

@Declan

while (stepper17.distanceToGo() != 3520);

will exit the loop immediately, because the motor hasn’t moved yet when this is first tested(i.e. distanceToGo is still 3520).

@Declan

while (stepper17.distanceToGo() != 0);

Suggest you try this, with your original code otherwise as posted.