Just to get a better idea of things, are you using the repository linked in the first few posts of this thread or my fork?
I should probably make my own thread for the fork. @florianz did contact me a bit ago and said he doesn’t have any time for this anymore and has essentially handed it off, giving me write access to his main repo.
I have looked at merging my code into his so this thread can be current but it seems like a cruel joke to stomp over something he might have working, as the original author.
Anyway, I will be better help if you use my fork, but his should be working too as of now as I pushed some necessary fixes to it. Did you ensure you enabled Oath in the SmartApp?