Beep Script step does work on all my devices. Tested with current FMGo 14 with iOS8*) on iPhone 5S and iPad mini (first generation).
Tests took place with test file hosted with FMPro 14 as well as with file on iOS-Devices:
I get haptic response AND sound for all circumstances.
Would you have any other, maybe older iOS-Devices for further tests?
If there's nothing wrong with your script AND the preferences set in your iPad, this issue might be narrowed down to iPad Air 2 only