Has anyone seen a problem where the screen is not showing any helium on main running screen. The unit runs perfectly and I showed our Cathlab staff that unit is showing internal tank value properly. I even opened K1 and K2 to let some helium drain. The system then briefly showed a value for the external tank while it was filling internal tank. But after completing the fill, it went back to showing nothing again for external tank. The mechanical gauge reads perfect all of the time.