Admin ‘PostTypes Permalinks’ display page won’t scroll

I help run a site that has 32 custom permalinks. When administering the Custom Permalinks plugin via the PostTypes Permalinks page, which lists the permalinks (by columns of title; type; and permalink), I am unable to scroll (advance) through to any of the following pages of listed permalinks. Another way of saying this is that the 32 permalinks are listed across 4 admin pages and I can only view the first page (though 20 permalinks are showing on the first page, which means there should just be one more page and not four, so this too appears to be adrift).

Specifically, two parts of the scrolling function won’t work: (1) The ‘screen options’ drop down (top right of the admin area) does not appear to work no matter the number of permalink items that are requested to show on each page; (2) the page scroll options (directly underneath the ‘Search permalinks’ field on the upper right of the admin page) won’t work either.

The plugin otherwise appears to work well.

The website running the Custom Permalinks plugin is within “Wordpress.com”. If I use v.1.7.1, the scrolling option works and I can access all permalinks. If I use any version from 2.0.0 onwards, the failure to scroll problem manifests itself. When I use the troubleshooting mode, the theme is swapped for Twenty Sixteen and I can disable 16 of 22 plugins. With the troubleshooting more, I can disable a further 5 plugins. At some point then, 21 of 22 plugins have been disabled (the exception is Jetpack (by Automattic) which WordPress.com won’t allow to be disabled). When a Custom Permalinks version later than 1.7.1 is turned on, the problem manifests.

Albeit that I can’t turn Jetpack off, but if you might have any other ideas as to what could cause this, I’d be very happy to hear.

Thank you for your time.

The page I need help with: [log in to see the link]