Will the MPX R1 foot controller TAP button control the Tap function on the G Force?
To our knowledge it is impossible to use that button to control the tempo, because of the reasons that Lexicon points out on their website. They use system exclusive controls for this button because they need to synchronize the LED´s on both their MPX-R1 and MPX-G2.
If you look at the factory board default settings for the MPX-R1, you will see that the tempo has not been assigned in the default settings, again for this reason as pointed out by Lexicon.
The only way to control the tap function of the G-Major is to assign one of the other buttons on the MPX-R1 via the MIDI learn function.