questions about snapping centers

Hi Friends,
        Here's the setup.  Snap the center of one object of a group (of 2 or 
more objects) to the center of a rectangle.

        If you use the option "Snap an item's rotation center", it won't work. 
Inkscape wants to snap the center of the group to the center of the rectangle. 
But if you use the option "Snap center of objects", it works like a dream.

        I've always assumed that the relatively new (well, new-er, anyway) "Snap 
center of objects" was meant for those unusual cases where the center of an 
object and the rotation center of an object are not the same spot.  But this 
behavior implies that perhaps "Snap center of objects" has a different purpose 
(than what I thought).

        Questions:

1 -- Is there a bug involved in the above scenario?
2 -- Exactly what is the purpose for "Snap center of objects" compared to "Snap 
an item's rotation center"?
3 -- Could the tootip text (for one or both options) be improved, to better 
represent how they work?

        I'm glad to memorialize whatever appropriate request is revealed about 
this, in a bug report.  I'm just not sure exactly which part needs improvement 
or might be a bug (the behavior or the button names/tooltips).

        (This was tested with Inkscape 0.92.3 on Windows 7 Pro.  Also I had all 
other snap options disabled, except for the snap center options, during 
testing.)

Thank you very much,
brynn