There are 2 possible reasons why KPI values are not being displayed on your KPI chart:

1. This usually occurs when the KPI is assigned a unit of measure that has a display factor of 0, hence the calculation becomes value*displayfactor = value*0 = 0.

 e.g. a Percentage unit of measure will have 100 as a display factor, so a value of 0.4568 becomes 45.86%. 

To correct this issue, navigate as follows:

Administration -> Units of Measure. (Leave the Display Factor blank or set it to a non-zero number)

Note that you will need to have role permissions to edit the measurement types

2. Values will also not be displayed if they are not within the specified Min and Max values on the Chart filters.