Still had the remote app on my phone and tablet, both didn’t work due to the ‘unlicensed’ error, with the only options ‘EXIT’ or ‘Go to the playstore’.
Downloaded the .apk from post 10 which stopped the ‘unlicensed’ error so I can operate Audirvana again.
Apparently there is a difference in the way this app checks things at startup.
Thanks @Damien for this intermediate solution.