There are a variety of reasons for the fluctuations and discrepancies in PPC or Amazon advertising data, as reported in Profits.
1) Traffic Validation: Because it takes up to three days for sales metrics to be validated in Amazon's Campaign Manager, the data Helium 10 accesses can fluctuate with each update.
2) Attribution: Some customers click on an ad and either buy the product immediately or click away to never buy it. But some customers click on an ad, then don't buy the product until later. Amazon calls that time period an attribution window. The attribution window for Sponsored Products is seven days; the attribution window for Sponsored Brands is 14 days. This time lag causes the PPC costs and sales data to fluctuate. If you have products with lagged sales, this will show up in the changing reports.