form not appearing on some mobile or websites

installed plugin and have had a few registrations.

Now the form is not appearing for some on computer or mobile versions.

I checked the Enable AJAX Search Functionality and Use PHP Sessions and was able to see the form on my moblie using safari but not google?

the google version has the thank you from the most recent person that registered on the site using the form

I had a user tell me they can’t see the form on their PC?

website
http://www.oktoberfestattheriver.com/volunteer/

https://wordpress.org/plugins/participants-database/