Search bar error message

Hello, we are using a search plugin called WP Fulltext Search Pro in conjunction with the Enfold theme. We chose this plugin specifically because it search PDF documents in the Media section of the site. When we begin to type into the search box it immediately gives the error message “Sorry, no posts match your criteria”. This is even BEFORE we press the find button to search. Once I press Find, the search works perfectly.

I contacted support for the plugin and they told me that the error message is not coming from their plugin. They say it must be another plugin or theme conflict. I switched to the 2020 theme and the error message went away.

I would really prefer the use the Enfold theme. Can you help me resolve the error message? Even if I could change the wording to something else that does not confuse the search user as it does now.

Below is a link to a screenshot of what I am talking about.

Thank you for your help!