error when filtering

Hi, the plugin was working fine at first but it has stopped working.

https://minivillenacalzados.es/comprar/calzado-respetuoso/blanditos-by-crios/?pr_stock=instock&wpf_fbv=1&wpf_dpv=1&all_products_filtering=1&filter_numero=24

If you look at this page, and select size 24, it says that there are no products with that size, but there are.

https://minivillenacalzados.es/producto/sandalias-pp975-gamo-rosa-palo/

what could be happening?