Cannot edit master slide in Mac

The master slide editable by me. I’ve opened a new Presentation document, and although I can select a slide master template, and implement it on the base slides, I cannot edit that master slide. Where it says “Click to Edit”, I try, but no change. I cannot delete the field. I can however delete the footer or page numbers.

Am I missing the “edit” radio button? Is this a Mac issue? I’m latest OS and LO7. Really appreciate help on this seemingly simple matter.

How did you try edit your master-slide? I mean what menu item did you select or something