Moving averages with RangeAvg(Above(...)) in Power BI

Gotchas and behaviour differences

• Do not write AVERAGEX(DATESINPERIOD(...), [Sales]). That averages per day. Iterate the month column as shown.
• AVERAGEX skips BLANK results, like RangeAvg skips nulls. A month with no sales is therefore left out of the average, not counted as 0. Use [Sales] + 0 if it should count as 0.
• Put the column used in ORDERBY on the visual's axis. If the axis shows another column from the same table instead, such as a month name sorted by YearMonth or a text key sorted by an index column, that column's filter stays on every row and the window shrinks to the current row. Fix both parts. Use SUMMARIZE(ALLSELECTED('Date'), 'Date'[YearMonth]) as the relation, and remove the label column's filter with REMOVEFILTERS('Date'[MonthName]) in the surrounding CALCULATE. Also don't call ALLSELECTED inside an iterator such as SUMX, where it returns only the rows being iterated. Compute it in a variable before the iterator.
• Qlik's version moves over displayed rows. The calendar version moves over calendar months, whether or not they have data.
• Visual calculations have limits that matter when you migrate: you can't filter or sort a visual by them, change their aggregation, or reuse them in another visual. Data exports leave them out. They don't support dynamic format strings or Show items with no data. Slicers, custom visuals and paginated reports don't support them, and you can't pin a visual that uses them to a dashboard or publish it to the web. If any of these matter, use the model measure instead. (Microsoft's list)