Error on site search

When the learnpress plugin is active, the site search functionality is not functioning.
So, when you enter a common word of phrase nothing shows up in the search results.
Also, the error message is now yellow and that is not a site wide color.

De-activating the plugin restores the sears functionality. Disabling cache plugins does not fix the problem.

What advice do you have for me?

The page I need help with: [log in to see the link]