Hi Naolkidanu ,
Thank you very much for your post.
If you are experiencing such anomaly it is most definitly an issue in your db. ATUM only reads the db and shows the values in that table. Try deactivating all plugins apart of ATUM and WC, try if the calculations work. If they do then is one of the plugins causing the issue. You can then start enabling one by one and check after each.
Pavel
