I've been making custom themes for my 360 for almost a decade, but I can't figure out how to get a custom "premium"-grade theme to work. I know that most premium themes from the Xbox marketplace have DRM and a license, but why don't my custom ones work? I would like to achieve this on a retail Xbox 360 if possible.
I do know how they work, right down to the formatting, dimensions, and color-range needed. Could this perhaps be related to the NTFS package that houses the theme's content? I did do some digging on this quite a few years ago and saw the term "strongsigning" tossed around, but I didn't find much on it. Any help would be greatly appreciated.