Hello,
so I decided to try out the portfolio feature with the filter. And I was unable to use it with Cyrillic symbols in the categories. The error I was getting on click is: “Syntax error, unrecognized expression:…..”.

So the problem is that if you create the categories in the portfolio page the category slug is set to the category name by default and your slug will have Cyrillic symbols in it.

So to solve this issue you can go in Portfolio -> Portfolio Categories select the categories and change the slug to Latin symbols.

Kind Regards, Nikolay