External Tools Missing From Ribbon

Anonymous 

You don't have external tools in Power Bi Desktop by default, you need to register the the tool in Desktop. Please follow the tutorial:

https://docs.microsoft.com/en-us/power-bi/create-reports/desktop-external-tools#dax-studio 

Paul Zheng _ Community Support Team
If this post helps, please Accept it as the solution to help the other members find it more quickly.

Even though another answer has been accepted, sharing my experience here as well, because this community post shows up in the top in Google Search results.

For me, the problem was exactly the same as you. What solved it is selecting Install for All Users during installtion of DAX Studio, instead of Install Only for Current user.

Hope this helps,

Nachiket