This can happen when the pressure in the keg is higher than expected. Keep the PerfectDraft Pro switched on and connected. Remove the keg from the tap unit, then reattach it to reset the volume gauge. The gauge should display an accurate reading after the next pour of more than 200 ml.
Additional recommendations:
- Always disable Stout mode before loading a non-Stout keg.
- Always store your kegs away from direct sunlight and heat sources, preferably at room temperature or below.