Page Builder Tab Not Loading on the backend of Previous Contents

Hi,
I have always used the Page Builder on my website without issue (I’m using the the following theme http://demos.themetrust.com/create/).

Today I wanted to edit some pages where I was already using the page builder but the tab is not loading. I see the content in the editor tab and visual tab but the page builder tab in not there. Instead, if I want to edit I page where I wasn’t using the page builder, the tab shows up and I’m able to move the content from the editor to the page builder.

This is a big issue for me, because I’m using the page builder in most of the pages of my website and in this way I can’t edit or working on them.

Please help!
Thanks