(Edit: Found the problem - a duplicate, modified LeftAndMain_Menu.ss template file that was overriding the one in the Subsites module. Sorted.)
I'm trying to get Subsites up and running on a substantial existing site running on V3.4.1 but have hit a problem with the UI: The subsite selection dropdown above the Pages tab in the CMS Menu does not appear.
Everything else about the module appears to be working fine. No errors are being thrown and I can't see any issues using Firebug.
I'm wondering if this could be a more general JS/AJAX conflict as I've noticed the little 'sticky-toggle' button that normally appears in the bottom left hand corner of the CMS Menu section has also disappeared. I don't think the disappearance is related directly to the subsites module but is indicative of an issue elsewhere.
I have a basic SS3.4.1 install with subsites working fine on the same local server. Both the subsites dropdown and the 'sticky-toggle' button appear correctly on this site.
Any insights or tips on how I could test further would be much appreciated.