Yes your right. Sorry about that. I never use the "Boolean Search" and just never noticed it was checked.

Thanks Vlad for your prompt reply.

It appears to me that you have "Boolean Search" option enabled. When this option is enabled, a minus sign is used to say that need to exclude all Notes that have the word "op" onside. Just remove a checkbox from "Boolean Search" option, and everything will work as expected.

I found that searching for somthing with a hyphen in it will not be found e.g. Co-Op but the search will find items that have an underline e.g. Co_Op.

I do not know if this a bug or a feature request.