There could be 2 reasons why you are not seeing efficiency data in your zones:

1. There are no live demands for all the junctions classified as Customer points. 
2. You uploaded live demands but there are some errors in the consumption data.

We use the following formula to calculate efficiency: (Consumption / Net flow)*100. If during the calculations the efficiency results are above 100%, the data will be hidden. 

We do this because a efficiency above 100% would mean that consumption is higher than the water injected in the zone, which couldn't be physically possible. Most of the times this is related with inaccuracies on the readings, so if you are experiencing this issue make sure to check your readings and try again with accurate data.