Local Time signature not applied when targetted onto the existing time signature

1.) Start with a grand staff score
2.) Ctrl+Drag (Cmd-Drag) a different time signature onto the time signature on one staff.

Expected Result: * The new time signature is applied as a local time signature
*Actual Result: The new time signature is applied globally

Adding to the confusion is that the highlighted drop target is only the single time signature instance on the target staff; giving the seeming impression that the time signature will be applied as a local one.

Workaround: Add the local time signature by any other method as described in the handbook (drag it within the measure/use Ctrl+click on the measure)