Weird display when clicking the exit cross button when viewing first article

After having installed the extension (Chrome), I made a search with PubMed, found an article, and the extension suggested me to add it to my pdf, greying the whole page and displaying tooltip and all the UI required. When clicking the exit cross on the right (because I was not acutally interested by this articles), the UI disappeared, but the whole page stayed greyed and I could not interact with it anymore :(