Not all tags displayed in search

Hi, i am a not native-english speaker, so please apologize. I will try to describe my problem, which I have using zotpress. I have a great collection of articles, books etc. I added on every item some tags. In zotero when I enter the searchbar with a certain word, there are those articles displayed, with the added tag. But when I search on my WordPress-site, only a few articles are shown, not all like in zotero. Does some have the same issues with tags?

best

Igor

The page I need help with: [log in to see the link]