Why does the cookie library conflict with the FacetWP plugin?

Question

JavaScript

The problem is this. There is a site. I decided to implement 2 cities on the basis of it. Through cookies. At the entrance, a person is asked to select a city, which is recorded in the browser cookies and gives information according to his city. The simplest option.

But. There is a FacetWP plugin - this is a filter plugin. It filters whatever you want. In my case, product. It works without reloading the page, as I understand it through a post or a get request, I don’t really understand this.
It looks something like this http://ss..net/?fwp=filter-fraza . But at the same time, the page does not reload, but simply shows the product I need. But. I noticed that due to the use of the cookie library and this city selection function, when I click on the filter I need, it seems to go to http://ss..net/?fwp=filter-frazaand the page is white. If I reload the page, then the filter seems to work. But here's the problem, why the page turns white. What could be the reason? Ajax cookies somehow jammed or what could be wrong? Thanks for any hint