Re: zoom ms 50 g : the tap tempo does not work
Are you sure it's not in "Tuner" mode? Check the "HOLD FOR TUNER/TAP" selection in the SETTINGS menu. While you're there, change the mode to TUNER, see if it works, then change it back.
Also, are you aware you have to press and hold the button for 1 second after you tap in the tempo to exit the "tempo entry" screen and get back into operating mode?
There is a fairly active Zoom forum where people discuss their patches, etc. They may be able to help you. IIRC, there's a forum room for all multieffects, including the bigger boards, not just dedicated to the MultiStomp series.