presently, space matrices have a width associated with them, chosen based on the settings of the stopbar in use at the time the position is set to a space in the MCA editor. Obviously, this can change based on mistakes in the stopbar or if a different bar is chosen at ribbon generation time. This can cause a mismatch when the spaces are found (in addition to showing a faint yellow tint in the MCA editor indicating a width adjustment).
Fixed space matrices shouldn't store a width; they should get their width from the stopbar in use. If an MCA contains this data, we should ignore it and not write it back out.