In order to have your Amazon Seller data in Polar matching what's displayed in Amazon's user interface, you'll need to ensure three things:
1. Fulfillment Status must be different from "Canceled".
On Amazon, orders can change their Fulfillment Status from Pending to Canceled. This implies that a past order could be taken into account one day, and disappear the next in Amazon's reports. This could occasionally cause very small discrepancies between Amazon Seller and Polar as the change will be reflected instantly in Amazon and will be visible with the next refresh in Polar.
With that said, when you're comparing the data between Polar and Amazon, we recommend applying the "Fulfillment Status" filter to only account for non-cancelled orders.
2. The Sales Channel must match the country (ex: amazon.com for US).
To ensure you're comparing data for the correct Sales Channels, apply the Sales Channel filter to only select the specific country that you're referencing.
3. The timezone must be America / Los Angeles for US, or Europe / Paris for EU.
Polar uses the timezone selected in your Account Settings to display Amazon Seller Central data (in Settings > General > Timezone). However, the data displayed in your Amazon Seller Central account will be in PST for all US merchants and CET for all EU merchants. When making a comparison between Polar and Amazon Seller Central reports, you'll need to modify the Polar timezone to America/Los Angeles (equivalent to PST) or Europe/Paris (Equivalent to CET), depending on the timezone of your Amazon account.