Thank you for contacting us.
I am sorry to hear that the Add Block button is not working correctly for you and our team is here to help in any way we can.
One potential cause that we have noticed in the most recent WordPress core version is a conflict created by Yoast SEO and our Easy SEO plugin. Having both plugins installed and activated at the same time disrupts the functionality provided by the Post and Page Builder and includes the Add Block button.
Try deactivating one of them to see if that addresses the problem you are seeing with the Add Block button. If that does not resolve the problem please let us know and our team will help you troubleshoot this further.
Customer support service by UserEcho