When paginating content, the nextPageURL() for Page 2 (when requested while on the 1st page) has doubles slashes before the page: portion. I would expect it to have only 1 slash (which is what all other pages have).
I would expect the search//page to simply be search/page.
For example, the Kirby website exhibits the same problem that I’m having on my site.
Maybe its 2 things working together? If you are forcing slashes on the end of URLS via .htaccess for SEO purposes (ie to eliminate duplicate content) and if the pagination always prepends a slash, you are going to end up with two I guess.
Are you doing anything like that? Strange that it doesn’t happen when you move back and forth though.