Hi Stephen,
Thank you for posting your question about editing the text inside a GridBlock. I’m sorry to see you’re experiencing issues. I’m not quite sure where you are at when you are experiencing the inability to edit the text. You should be able to navigate to Pages > All Pages. Select the Page with the text you’d like to edit. Once you are at the Edit Page window, ensure that the “Visual” tab is selected for the editor. If you are set to “Text” then the GridBlocks are not displayed. As long as you are using the visual editor, you should see the GridBlocks as you hover over the text and click on it to modify the text.
I hope this helps! If you are attempting to modify text and persistently having issues. Please let us know where (Customizer, Posts Editor, Pages Editor, etc) you are experiencing these issues, so we can look into it more.
Sincerely,
Carlos E