As a part of updating WordPress.com to 4.5, we noted that a small but important change to the version of jQuery in WordPress may have affected a number of VIP themes using an outdated syntax for selectors. This would have been acceptable up to jQuery version 1.1:
$('.class a[href=#foo]');
But for versions 1.12 and on, it needs to be written as:
$('.class a[href="#foo"]');
with quotes. We’ve preemptively updated all of the occurrences of this syntax that we could find in VIP themes, on both WordPress.com VIP and VIP Go.
You’ll want to make sure the change is made in any development versions of your themes or other code where it might be in use. You should also make sure all of your dependencies are compliant with this jQuery update.
If you have any questions about this, please open a support ticket.
WordPress VIP Lobby 