I am building a dataflow to transform an Excel document (hosted on Sharepoint) into Common Data Service (Powerapps data flow, not PowerBi). Every now and then the data flow crashes while i'm building... usually while adding a custom column. Once the crash occurs, I cannot browse any of the previous steps in the transformation. I have to navigate away from the transformation (into the map tables step), then back again. Then I have to delete the step I just created. After that I can keep going. Difficult to reproduce, but very annoying.