SocialXT.Share yielding different results depending on device

On iPhone 5, everything in the activity sheet expected shows up, and everything works as expected. On iPad 2, 3, and mini, only mail shows up on the top row (missing social applications), and when one presses mail, share is immediately completed with ShareCompletedEventArgs.completed = false, without going to mail screen. The bottom row in the activity sheet – save image, assign to contacts, etc. work as expected.

I am sharing a photo (Texture2D).

Same as U3DXT SocialXT.Share yielding different results on different devices - Unity Answers