I also observe this behavior. It is really annoying. I can say that it happens only after unlock. If Enpass has been already unlocked, the Assistant keeps the results filtered by URL. But if I lock it and then close it, and then reopen and unlock it, initially I see the item I need for the current website and immediately after that the results get refreshed and I see "Most recent items". I need to close and reopen the Assistant again in order to see the correct item listed.