Hi Satrya, thanks for nice plugin!
I have the same problem. I wrote to Limit to Taxonomy box “category=uutinen” and tried “post_tag=uutinen”. “uutinen” is the slug name for my category. Does it not work with slugs? I didn’t find any ID numbers to separate the categories from each other. I’m not using cache plugins.
When I put the “category=uutinen” nothing shows up and when I don’t write anything every post show up. I tried other slugs also.
Thanks!