Greetings,
You’re welcome! Hmm, yes, I think that is a known bug (or was a known bug at the time that I did the sample app) which I have unfortunately not reexamined in a while. It would need some time set aside to create a few new installs in order to investigate why the callback isn’t received as expected (or possibly, why the sample app just doesn’t do the right thing, which is the second possibility). It could be a while before I have the opportunity to look into it – are you able to use the workaround for the time being?