I have come across an issue with 'Stock Exceptions' and for some reason I get blank.
If I set the Summary method as Sum, then it works but the task clearly says it should be kept None.
I am attaching INV03, INV01 (source) and SKU08 if you can think if I did anything wrong there.
But we are asked to make it None in INV03 hence my whole confusion. Let me read the instructions again.
I'm having the same issue - I'm beginning to believe it's just a typo in the training