Clicking on tag to filter by it breaks tab navigation

Hello.
I have 3 main pages and 3 tabs that lead to them.
Their urls are:
http://appgranula.com/PORTFOLIO
http://appgranula.com/TENY-I-SROKI
http://appgranula.com/SVYZ-S-NAMI

And I have more secondary pages that have some tags attached to them.
If I click on one of a tags, I am being routed to the following url:
http://appgranula.com/filter/дизайн

And filtering also breaks tab navigation, because tab urls become:
http://appgranula.com/filter/дизайн/PORTFOLIO
http://appgranula.com/filter/дизайн/TENY-I-SROKI
http://appgranula.com/filter/дизайн/SVYZ-S-NAMI

However this is not breaking all the site, but it affects filtering of elements of a page.
This way, if one of secondary pages has not been marked by tag "дизайн" it won't show on a page.

I believe the problem is in constructing of href for anchors you use to make tabs. Don't include /filter/bla-bla url and everything will be ok.