ImageBrowser next and prev buttons do nothing after update

We’ve just upgraded to NextGEN Gallery v2.0.63 from v2.0.61. We’re running WordPress 4.0.0. We have old-style imagebrowser galleries using the [imagebrowser id=”x”] shortcode. This gallery has existed since 2010. The site in question is a subdomain multisite using Day and name permalinks.

The gallery in question is inserted into a page. Although the primary image displays the next and prev buttons do nothing. We’ve noticed that the link structure has changed between the two versions. Under 2.0.61 the links were formatted like this:

http://your.subdomain/nggallery/image/your-image-slug-here/

Under 2.0.63 they look like this:

http://your.subdomain/your-page-here/nggallery/your-image-slug-here/

Clicking the link has no apparent effect, although after clicking several times the link is rewritten into this bizarre string:

http://your.subdomain/nggallery/pid–/pid–/pid–/pid–/image/

Needless to say this doesn’t work. I didn’t see anything obvious in the changelog for this version to explain this issue. The issue is also present in 2.0.66.33, but first occurred in 2.0.63. There are no errors in the PHP log. We’re testing this on a development server which is not publicly accessible. I tried using the new-style shortcode ([ngg_images gallery_ids=”88″ display_type=”photocrati-nextgen_basic_imagebrowser”]) but this had no effect. We have AJAX turned on. Resetting options disables the AJAX but otherwise has no effect: the page loads with the incorrect URL (pid–/pid–) in the address bar.

Any guide as to what changed and how we can get the old behavior back would be appreciated.

https://wordpress.org/plugins/nextgen-gallery/