Hey Donna,
Thank you for reaching out to us!
It looks like there’s a plugin or theme conflict causing this problem, specially because I’m not able to reproduce this error in my own local WordPress install.
To get started, please open up your browser’s console and verify if there are any relevant javaScript errors in there.
If you find an error, I would recommend you to run a Conflicts Test. You can start the test by temporarily changing your theme to another one like Twenty Seventeen and let us know if the problem is solved after that (don’t forget to backup your database before changing anything).
Let me know if you have any other questions in the meantime!
Thanks,
Patricia