Thank you for contacting us!
I am sorry to hear that the Post and Page Builder isn’t working for you after forcing HTTPS on your website, but fortunately our team has a solution for you!
The error you are seeing is likely happening because of the Site and WordPress address URLs configured in your website’s General Settings. If you forced HTTPS elsewhere, but did not change the protocol used in those URLs, then script that loads the Post and Page Builder interface is probably getting blocked due to mixed content errors.
Our team create a quick plugin for this issue that forces the editor’s script to load from HTTPS and should restore the Block features. I hope that plugin works for you and please let us know if there is anything else that we can do to assist you.