Jay and Peter:
My 2 cents:
I was able to reproduce the problem by selecting the Cab Base 1D object in the Kitchen Cabinets 9 folder and setting the Sink Style parameter (under Sink and Tap) to "None". I placed this object, selected it, opened the object settings dialog box and navigated to the Bathroom Fixtures 9 folder to transfer the parameters of the Cab Base 1D object to the Basin Cabinet object. This also transferred the hidden parameter that Peter discovered. This can be undone by selecting the problem object, opening the settings dialog box, selecting some other object, and then reselecting the Basin Cabinet object; this has the result of resetting the parameters (including the hidden ones) back to their default values, the parameters will now need to be changed to get the desired appearance. Changing the default parameter values by opening the object will not affect the parameters of an object that is already placed in the project.
It makes sense that all parameters are transferred (even hidden ones), but this object has a bug in that particular parameter since the sink cannot be eliminated as it can be with the Cab Base 1D object.
Interesting problem, in that it shows that hiding a parameter does not eliminate its consequences. I hope this helps.
David