I wrote already on or two times: assignable buttons are currently not displayed on iPhones in portrait mode. That will change when I rework the assignable buttons panel and make the buttons less wide. I think it will then be possible to display 2 in iPhone portrait, 6 in iPhone Landscape and 4 in iPad portrait and hopefully 8 in iPad landscape.
As long as you don't see anything in the changelog about this, don't expect anyhting to change.