Thank you so much!
This will teach me to not use symmetry when attaching moving parts in the future.
In my case, I had to change three instances of True/True to False/False to make it work. Logically, both should result in the same rotation direction, but it resulted in a non-moving servo.
While the "inverted" parameter corresponds to the "Invert Direction" toggle in the editor, there doesn't seem to be any editor representation of the "mirrorRotation" parameter. I suppose it is set on part attachment with symmetry to prevent problems with mirrored symmetry on parts like wheels where expected dynamic behaviour is not to be mirrored. Removing parts from symmetry does not affect this parameter.
