Using nopC 4.30
To duplicate.
1. Add a new product.
2. Set inventory method to track by product attribute.
3. Add a priduct attribute.
4. Generate all possible attribute combinations.
5. Add stock quantity to the attribute combinations.
6. Check the Low stock report.
What you will find is all product attribute combinations show up on the low stock report even though the attribute combinations have a quantity above the minimum threshold to display on the report.
Also, it doesnt matter how many attribute combinations you have with valid quantites. They will all show on the report anyway. :/