The Global Demand Assumptions Dashboard Example has a line chart that is out of sync with the DEM03 grid displayed below it, but the course instructions specifically instruct us to "Sync the chart by Account and SKU".
The 2 DM03 screenshots you provided below are the same. I was expecting to see a different dashboard where the data is not matching so I can help figure out where the discrepancy is. If you can provide another screenshot that would be helpful.
In the meantime here is a point that may help. If your data on the lower level of a hierarchy (List of time) matches but it doesn't on a higher (aggregated) level, then the issue is not in the formula as much as it is in the summary method.