This is clearly a *bug* and needs to be fixed. It has to be something fairly simple, as well. I can share just fine with other mobi books or just about anything that wasn't processed in any way by Caliber, but the instant Caliber touches anything it becomes impossible to share it on Facebook. My assumption (like a lot of others) was that Facebook sharing wasn't supported by any document that wasn't purchased for Kindle, but that isn't the case.