I am in a position where I am trying to map my own 'shift' button so that I can switch between my own custom mappings. Now, there are several ways to go about this, but I believe I found a bug whilst trying one avenue.
Of the 8 buttons on the left hand side, only the Stop and Play buttons can be reassigned. (personally this is aggravating, as one should be able to avoid your firmware when those functions are not required but I digress). In order to use them as I please, I manually reassign them as a Midi Note.
However, when you go to actually use them, the MMC signal is still being sent anyway. You can reassign Play to a new midi note, but it will continue to send the Play command. Hell, you can specify your own note, but Play will ALWAYS revert back to D-2. Also, the note value as received by Traktor is a different note completely. I set Stop (as Midi Notes) to F8 and Play to G8. However, once in Traktor the Stop is apparently F9, and Play is apparently now D-1. And it STILL keeps sending the Play MMC message!
Even more retarded is - you can disable those buttons completely, or change them to a different MMC function. And they will still forever be Stop & Play.
Also, attempting to upgrade the firmware has lead to Midi Control Centre bricking the device and locking it in firmware mode - apparently once it places it in FW mode the best I can hope for is a 'device in use' error. It is impossible to resync to MCC because it is now permanently 'disconnected'. Thanks for the expensive paperweight- at last I have an Arturia product that functions effectively.
Beatstep has some serious shortcomings that can usually be worked around, but the list just keeps on growing. For such a simple piece of hardware, you managed to make a virtual clusterf*ck of almost every aspect of it, and I've been one of the few Arturia apologists left willing to play Devils advocate. No more.