Thanks for the plugin suggestion Author,
Results of the tests:
Deactivated the old plugin and installed the Custom Post Type UI. Created another taxonomies.
When I use checkbox
in the first taxonomie and select
in the second, it results in “Nothing Found” page. And when I check the 2 options in the first taxonomy (and the second taxonomy is set to All) it searches only the first option, not both (i.e not searching combined)
Any possibility to the problem be related to “checkbox” option? Because when I change the first taxonomy to select, it results OK …