Inconsistent search and double take

I recently created a new website for a client, with the same members area (through UM) included and transferred all their Ultimate Member profiles and the 2 directories across to the new site. I reviewed all the settings and believe I have set the new site the same as the old site.

I used the same code on the public ‘find a teacher’ page as on the previous site and didn’t make any changes to the login page produced.

Issues (tested in Firefox and Edge):
When I log in, with the correct username and password, I get an error, “An error has been encountered. Probably page was cached. Please try again.”, when I try again, I get logged in, no error.

Once I am logged in as an admin, I get correct results when I do a search of a name or key word in the ‘find a teacher’ public page or the ‘find a member’ in the members area.

When I go to the ‘find a teacher’ page, without logging in, and do a search for a name I know there are results for, I get “1 Members. We are sorry. We cannot find any teachers who match your search criteria.”
If I refresh the page, I get the correct search result.

This is a really important part of the site and where we had hoped to add more diversity in the search ability but I need to get the basics working.

Any ideas would be greatly appreciated
Karen

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