Zoom into Region not working on mouse 18.12.7

I wonder if someone could confirm this bug for me, so I know I don't have a hardware issue.

One of the places I work recently upgraded to Media Composer 2018.12.7

I usually map the "Zoom into Region" command to the Mouse Button 3 (pushing down the scrollwheel).  It seems in this version of MC, that no longer works.  I can map it there okay in the Mouse Settings, but it does not function.  Other commands work fine on the same button.

thanks.