Thank you @uxl !
The ‘Post Content’ block was indead missing. Now I can move forward. The content I put in is visible when I render the page.
I started by copying the ‘Page (No Separators)’ main ‘Group’ block into my page template, and will continue from there to make my customizations step by step.
So thank you for your assistance!
PS. I still have to find out why the Page editing screen displays an 8.5 cm margin from left to Post Content when editing. In the Template editing mode the margin is only 1.7 cm from left to Post Content?
