I'm not sure if this is bug or by design but the native KPI visual is only displaying the latest value of a measure given. For example if you have table:
Label Value Date
A 13 1/1/2018
B 43 1/2/2018
C 32 1/3/2018
If I create a measure (or even just use the column for an implicit measure) and place it on KPI in indicator field, the value displayed ignores the measure calculations and only displays latest value. THis is confirmed by clicking on three dots on KPI and showing data in table to see KPI is only displaying the latest. In this sample table, it would display 32 since Date column used for trend axis.
My expectation is the KPI should display and honor whatever aggregation I place. For example if I made a measure that did AVERAGE(value), and placed it on KPI, it should display the overall average of the value, not the latest value. In my customer's data the KPI is ignoring explicit/implicit aggregation options and only displaying latest value. Hope this makes sense.
NOTE: I cannot share customer data file. This is using latest PBI desktop build, x64, version 2.56.5023.1021 (March 2018). OS is Windows 7 x64.