So far no one came up with a solution. So I guess the option "stretch to fit width " is completely useless, unless you compromise with the pages jumping and resizing in variants. I've spent days trying to find a solution but there isn't any, as this is just a bug and I just waste my time.
Acorn give me some advice, which I followed to the letter but nothing worked. I even test it with a blank page with no content and still the same. STFW it does not work as intended. The other thing is baffling me is. How everybody is happy with this and actually highly recommend the "stretch to fit width" feature, when they very well know it doesn't work?