Hello,
I've found that after creating a Data Merge Layout that I am unable to change the number of columns, rows, data offset and more. At this point, I have to create a new DML each time I need to adjust this information, moving my the content from my original DML to it after. I've attached a screenshot of what that toolbar shows when selecting the DML after it has been created and deselected.
Perhaps I'm missing a way to access this information, but at the moment it's quite disruptive.
Additional info: I'm running Windows 10. The issue occurs even in new documents. Though it occurs on each document I create, I have attached a new sample document that I created to test this.
Thanks
SimpleA5Booklet.afpub