VM2 Search - Results problem with 'Search Filter Category' ON

[clicky]

Page 2 onwards of search results shows no products when 'Search Filter Category' is set to ON.

Page 1 of results displays products correctly and the pagination shows correct number of pages for the search result.

Everything works correctly when Search Filter Category is set to OFF ie. products from all categories appear on Page 1, 2 etc. but I need to limit the search results from just 1 category.

Pls. Help