I'll leave this here for anyone else who is experiencing the issue. Even though the play store said that Evernote was installed on my device and didn't show me the option to update I clicked on the installed button and choose my LG G3. The app installed itself and is now version 7.8.2 and most importantly the doc camera works properly again.
I'm still experiencing the black image if I try to save it as a document. I don't see any option to update my Evernote version in the Play Store either. LG G3, Android 6.0, Evernote 7.8.1