Not sure why this window doesn't show in the treebar, unless you're looking in the wrong place, or else if you have some other command elsewhere that's hiding it.
You're using the -z switch, which means the window is at the tail end of the switchbar, and is at the bottom section of the treebar. Even if you've collapsed that section in the treebar, clicking on the @siteop icon in the switchbar should jump the treebar's cursor to the bottom section and expand it.
If you have something which does
/window -w1 @siteop
this setting makes the window visible in the switchbar but is hidden from the treebar.
