Mac OS X version 10.12.1
I'm using Subform 0.0.0 8afa768 on Darwin 16.1.0 and am having trouble when duplicating artboards. When I duplicate an artboard that's 1200px wide instead of it appearing next to the original artboard like it does at smaller sizes it appears directly over the top of the original.
Steps to repeat:
• New document
• Change artboard dimensions to 1200px wide
• In structure right click the artboard and click duplicate.
It looks as if nothing has happened but if you drag the artboard you realise the original is directly below the new duplicated artboard.
UPDATE — 05/12/2016
Also noticed that if you have 2 artboards side by side and you increase the left hand artboards width, it overlaps the right hand artboard rather than pushing it further across to the right