Why do I have to press my footswitch twice to access Tap Tempo or Bypass, on the G-Major, G-Force and D-Two?
It seems that you're not using the ideal pedal type for this. You're probably using a "latch" type pedal - this is the kind that stays on or off, when you press it once. Now, that works fine the first time you press it, provided that it was set to "off" before you touched it.
The following times however, the pedal needs to be switched off again before it can be switched back on, and thus produce an impulse that your unit will recognize. That's why you need to press it twice.
We suggest that you replace it with a "momentary" type pedal. This pedal type switches to "off" immediately, or when released - and is therefore better suited for this purpose.