When user will activate search box in 1Password iOS and start typing sometimes results are not visible because they need to be scrolled down - so user thinks that items were not found. I have noticed it on iPhone many times.
Thanks for taking the time to write in with this! Unfortunately, the issue that you mention is a known bug, and our developers are working to get it behaving correctly. I do apologize for the inconvenience here, I know it can be a bit confusing.