If you are having issue with category / tag then follow the tips bellow :
1) Check the post configuration and make sure you are using the correct settings make for tags and categories.
For Tag :
tags For Category :
2) Check the text what you are using as category / tag. It should be english ( Bug Report Here : https://github.com/sverrirs/jekyll-paginate-v2/issues/171 )
3) Make sure you wrote your tags and category with comma separted.
tags: [wordpress, jekyll, ghost, themeix]