In May 2017 Power BI Desktop started supporting creation of DAX measures when working in live connect mode to an external SSAS model: https://powerbi.microsoft.com/en-us/blog/power-bi-desktop-may-feature-summary/ Vote on this idea if you want support for calculated measures against multidimensional models too.
This idea was shared by the Power BI Product Manager, and is one of the top ideas, yet there has been no update for almost 2 years. At least give us an update please.
Please include this for multidimensional cubes as well. Within Excel it’s possible- why not within PowerBI?! Only then we can use PowerBI for our customers...
This is needed to get data from an SSAS cube into a Power BI visualization. I was genuinely surprised that this functionality was not already in Power BI.