While dockingport:ISTYPE("DECOUPLER") returns true for docking ports, a downtree part doing a PART:DECOUPLER does not see docking ports as their decouplers.

Whether staging is enabled on the dock port makes no difference, which is ok for most purposes as one may not care if it is staged or not, but one would think that especially in the case where the docking port was in the staging sequence that is would be logical for PART:DECOUPLER to recognize the port as the decoupler that will separate part from the main craft as it is fairly clear.

I'm thinking that whatever nearest uptree part for which ISSTYPE("DECOUPLER") is true, PART:DECOUPLER should return that part whether it is staged or not as staging is an entirely different consideration when scripting vs normal play.

Forgot a big point. This issue definitely happens when ports are in the PREATTATCHED state but I still need to test if it is true for craft that were redocked after the initial undocking. So this may just apply to ports in the PREATTACHED state