I am struggling with Total Beginning Inventory because it is going pretty deep into negative as weeks move on so I think I messed up somewhere.
'INV01 Inventory Ordering'.Beginning Inventory[SUM: 'SYS08 SKU Details'.Supplied By]
That's a good thing. It's because you haven't loaded the receipts yet. Since the sales forecasts are there and your balance set EOP = BOP+ Receipts - Sales, you're inventory will continue to drop. Once you load the receipts (which you won't do until one of the sprint exams) these will be negative.