The VV may be broken then, if it is intended to indicate slip/skid when uncaged.
I tested using an extreme asymmetric loadout to induce slip/skid, FL20, no wind, A/P ALT/HDG.
Uncaging/caging appears to indicate slip/skid, as expected.
Countered slip/skid using rudder, ball now centered in slip indicator.
Uncaging/caging appears to indicate same slip/skid as before, e.g. rudder didn't change VV movement.