@shanebp I activated different themes on a test site, and replicated the issue with WP 2015, as Dan confirmed. However, the issue did not persist when using Genesis, 2013, or Flourish (Genesis Child Theme by Restored 316).
The theme being used on the amongstlovelythings.com site is Beautiful, a Genesis Child Theme, albeit an older one.
Yes, this is the search widget built into bbPress.
We deactivated all plugins except for bbPress, and it worked fine. Next we activated BuddyPress, and it quit working. Even when those are the only two plugins active, it doesn’t work.