There seems to be a bug in the values displayed in the properties panel for layout scale. I have model units in Feet and layout units in Inches. In the panel it says “[ ] inches on page” and “[ ] feet in model” but appears to show inches in model (the value is multiplied by 12). In the screenshot, I have 1" = 20’, but it is showing 1" = 240’. The actual layout is indeed in 1" = 20’, so it seems to be a value error bug.
Also, if I enter 20 into the feet, it will scale properly, but the value in the panel will be x 12.