Alon Ohayon looks for the missing month:
When you’re using Power BI, you probably create line charts that show data by month pretty often. It usually works great, but what happens if some months don’t have any data?
By default, Power BI just skips those months in the chart. That might seem okay, but it can actually be misleading—especially if you’re looking for trends over time, including the months with no activity.
Alon shows us an example of how to do this in DAX and that works. But if you can solve this at the data layer, such as when querying from a SQL Server, that’s even better. This happens to be one of the good uses of a calendar table: giving you a complete set of months (or whatever time period you want) that you can then use to left join to your data, returning either a data point with a value, or a NULL that you can coalesce with 0 to ensure that you have a result for each month.