XNPV gives same result for 2 different time series

I have 2 different time series of 8400 values.  As per the figure below:

However the calculation of XNPV is exactly the same for both series as shown in teh figure.  The code for both are shown below:

Scenario 3 NPV (Total) = XNPV('Scenario 3 (Time Series)',[TOTAL (Scenario 3)],'Scenario 3 (Time Series)'[Date],0,08)

 and

Scenario 1 NPV (Total) = XNPV('Scenario 1 (Time Series)',[TOTAL (Scenario 3)],'Scenario 1 (Time Series)'[Date],0,08)

The same calculation in Excel with the same two series results in R745 081 242 for Scenario 3 and R1 021 094 189 for Scenario 1 which is correct.

Summing the two series provides different values as shown in the figure so they are definately different series.  Not sure how to fix this glitch.

Any advice?

Paul