I am currently doing the Level 2 Model Builder, Sprint 1, and I am stuck at step 1.5.7
Basically, I need to feed a boolean Line Item called "Has Data?", which is on the SKU ; Account dimensions from a numeric Line Item called Volumes, which is on SKU ; Account ; FY19 dimension. Therefore, I need to aggregate the data on the time dimension, using a ANY aggregation method to retrieve a boolean value.
If I remember correctly you should just be able to use Timesum('DAT03 Historic Volumes'.Volumes) without any further values and meet the 'Has Data?' flag requirements. Effectively this will just remove the time dimension from the original value and flag the true/false per account for you.