Originally Posted by daveryanwyoming .
I'm not sure of the specifics of what you're seeing but I expect it has more to do with the way the periods over which NP is calculated are selected. For instance there's no function in the ride file that selects the best 20 or 60 minute NP, instead WKO+ finds the highest AP for 20 or 60 minutes then also displays NP for those segments. It's entirely possible that there are other segments of the file that have a lower AP but higher NP.
Another possibility is that you're seeing NP for segments that span rest breaks in one set of charts and those are being filtered out in the other charts. Hard to say without digging into the data but FWIW I have seen small differences as in a watt or a few watts difference between peak NP reported for a given duration on a ride and what I see if I chart peak NP for the same duration in a custom chart. The differences have been so small and usually on the order of PM accuracy that I don't worry about it. If you're seeing much larger differences you could dive down into the data a bit to see what's happening and do things like break up files into smaller chunks or export the data to Excel for some data mining but again I wouldn't bother unless the differences are big enough to influence training decisions.
-Dave