Problem with Moving Annual Total

Patrick_Knobel, thanks for including the image of your desired end result. It is very helpful. It's clear now what you need.

Here's my reproduction of your visual:

A few things to note. The visual is a stacked column. The axis labels are simply my months. The measure is a simple SUM( FactStupid[Amount] ). The legend is my DimProduct[Model]. The only special sauce in the whole setup is a visual-level filter on my field DimDate[Rolling 12M] = True.

It looks like you've got fields in your date dimension already that can help fill this role, if not, it's trivial. Here's my DAX for the column:

Rolling 12M = 
VAR
	CurrentMonth = 
		LOOKUPVALUE(
			DimDate[MonthIndex]
			,DimDate[Date]
			,TODAY()
		)
RETURN
DimDate[MonthIndex] >= CurrentMonth - 11
	&& DimDate[MonthIndex] <= CurrentMonth
	

Where [MonthIndex] is an incrementing counter that indicates the number of months that have passed since the beginning of my calendar. In Power Query, here's how I create [MonthIndex] (as a custom added column):

= let
  Mult = [Year] - List.Min( MonthNumber[Year] )
  ,Index = 12 * Mult + [MonthNumber]
in
  Index

'MonthNumber[Year]' is the reference to the [Year] column in the previous step in Power Query. MonthNumber, in that context, refers to the name of the previous step.