Sparse Data and the ALL(Variable) function produce inaccurate totals.

When Using the ALL function to try and create a sum across categories I get an erroneous result.
This error has some odd behaviour:
-It only shows up when the underlying data is sparse

-It only shows up for some of the rows, even when they're within the filters excluded by ALL

-It's not present when using ALLSELECTED, despite not having any relevant external filters

-It dissapears when changing one table column from date to date-hierarchy

I have created a .PBIX with simplified data to illustrate the issue here: https://file.io/qRkApG5mevv7 https://drive.google.com/file/d/1uMZ20U52LhunlAu2ytR4tj4CEIiWlz08/view?usp=share_link