How I fixed Bitmoji after the iOS 10 update
Just disabling and re-enabling the Bitmoji keyboard in Settings did not work for me. Here is what I did:
To get the Bitmoji app to start working again in Messages I took the following steps:
Settings>General>Keyboard>Keyboards - Slide left on Bitmoji keyboard to actually delete it.
Then, I selected "Add New Keyboard" and selected Bitmoji. Now its working fine!
iPhone 6, iOS 10