I just ran into this today, perhaps it's new with the 12.15 firmware release. When configuring a data field, if I select Connect IQ, instead of the list of Connect IQ fields on the device, I
see a completely blank display. Tapping the display returns me to the screen where I select which type of field to add. Oddly, I can still configure Connect IQ fields from the Connect app. But from the Edge itself it completely fails.