Hi Jimmy, sorry for delay.
With the present version of the apk, 4.1 will not work. A lot changed between 4.1 and 4.3. I’ll put some effort in to backporting the app when there’s more time but can’t make promises for that particular Android version and phone: one of the biggest changes between 4.1 and 4.3 was unifying the bluetooth API, before 4.3 it’s much more manufacturer-specific.
Sorry to keep you waiting, let me know if there’s a way I can help sooner. James