J-BusinessDirectory - Keyword search includes now also the category name

I assume this is related to the option Search Field in General Settings -> Business Listing

I did some search test, and still don't understand the behaviour, especially when more keywords are used from different Search Field

For Example:

Category: Recruitment

City: Willemstad

If single keyword is used, results are showing correct listings

If two keywords are used, like Recruitment Willemstad, no search results are returned.

With multiple keywords, seems that only when both are in same field will trigger hit. And if keywords are in different Serach Field isn't working?

Can you explain how the search is working?

Brgds, Robert