Reza Rad has a workaround for us:
If you use a streaming dataset in Power BI, you cannot download the Power BI file, and you cannot open it using Power BI Desktop. This means that you are limited not to use calculations in a streaming dataset. However, there is a small trick which you can use and can be helpful. I will show you that in this article and video.
Click through for the article, which includes the video.