Hello nopCommerce Team,
I just found that reward points functionality is not working for orders in nopCommerce 3.90 and 4.00. I checked it with nopCommerce No Source version on Local IIS.
For all other features, reward points do work correctly.
Steps to find this issue:
1. Make sure reward points are configured properly for orders on /Admin/Setting/RewardPoints and Enabled as well.
2. Go to your My Account page -> /rewardpoints/history to see your previous balance.
3. Add some product to your Cart and complete checkout.
4. Go to Admin -> Order -> Edit (The order that you placed)
5. Mark Order as Paid and then Change Order Status to Completed.
6. Go back to Step 2.
You will see that no reward points has been added automatically.