Filter by issue

Recently I updated my Sampression Lite theme to 1.5.1 (yup, only recently 🙂 ), and after that the filter on the front page started behaving strangely. It showed all the posts by default, but when I clicked on any other option (category), it did not show anything at all.

My first idea was that I messed up something in my child theme, so I switched to parent Sampression Lite, but the problem stayed there as well. On further investigation I found out that some of the posts get shown. It seems like the filter works only for first page – e.g. filters only the first page, but ignores older posts.

My site is http://girl-gift.ru

Any help regarding this problem as well as any ideas where to search for answers is highly appreciated. I really love using Sampression Lite, and I would like to resolve this issue 🙂