sorry the images are with Persian words. if you note at the red circles, I hope you can see the wrong behavior.
if I go to the search page and I search a word, I’ll find some entries for it:
if I want to do the same search in a specific category using the advanced search it gave me wrong results:
as you can note it didn’t find anything. though in the first image, the first entry is from the same category selected in the second image.
if you go to the category page, and search in the category for the word, you will see the correct result: