Problem with "Not" as a search qualifier

Colleagues: I’m having trouble with multi-line searches if I use “not” as a qualifier. For example, in the following search (here I capitalize my search words): Keywords Contains IMPLANTATION And Keywords Contains SONIC I get 317 results. But if I change the search to: Keywords Contains IMPLANTATION Not Keywords Contains SONIC I get a message “No matching references found” (even though there are some). Similarly, when I use the search: Keywords Contains IMPLANTATION Not First Author Is PLUMB I get 3 results that all have Plumb as a co-author, but none of the references that have Plumb as a First Author! If I search: Keywords Contains IMPLANTATION Not Author Is PLUMB (or Not Author Contains PLUMB) I get the message “No matching references found”. It is like “Not” has been disallowed as a search modifier. I am using EndNote X7.3.1 in a windows system. Any ideas?

Whoops, looks like my problem was solved by a simple restart.  I apologize for my impatience.

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