native.newTextField()'s are native objects. We are at the mercy of how they behave on each platform. Windows, macOS, Android, and iOS are all different operating systems with different ways of handling native elements.
Therefore fading may work on one platform and not another. Because it’s inconsistent we have to go with the worst case and say fading isn’t supported. If you’re only building for one platform and it works for you, great, but we can’t guarantee it’s going to work everywhere.
Rob