iPhone airplane mode bug?

For some reason every time I try to send pictures via iMessage with airplane mode and wifi on, it won't send and changes the contact back to text message. There's absolutely no way to change the contact back, other than them texting you via iMessage (because they still see iMessage). I've tried turning iMessage off and on, resetting network settings and restarting the phone. Is this a bug or just happening to me?

An example: You could turn your phone on airplane mode and turn wifi on, and text anyone with iMessage (including yourself), and it'll work fine. As soon as you try sending a picture via iMessage, it'll say you need to turn off airplane mode or text using wifi and immediately turn that contact into text messaging. There's absolutely no way to change that contact back to iMessage. I just tried it on myself (own number, iMessage) and now it's also stuck on text messaging. I can't text myself via iMessaging cause I can't see iMessage, only text message. Is this a bug or only happening to me?

I would appreciate if someone could try it out and let me know if it's happening on the latest version (iOS 9.1) on their iPhone. I'm using an iPhone 5S in case it may be a specific version big.