MFP requires using Intiface because of how The Handy api is made. When using the normal “The Handy” output in MFP each command has to go thru their servers. That makes it is incompatible with live playback. When you use Intiface just make sure to switch from FixedUpdate to PolledUpdate after adding The Handy mapping and it should be smooth.
HereSphere or other The Handy apps upload the whole script to the device, so the device plays the script not the app.