Try this:
https://data.nbn.org.uk/Search?q=Recording+scheme

First page says "Showing 1 to 25 of 57 entries"

Click on "Next" and it says "Showing 0251 to 57 of 57 entries" and Next button is enabled but does nothing, although Last works.

Alternatively refresh the search and click on "2" and it says "Showing 26 to 57 of 57 entries" but only shows 26 to 50 and, again, Next button is enabled but does nothing.

This is a very long-standing bug.