gjross
Well, I do not know that we have a spefic row limit. Nevertheless, the files should not exceed 250 MB, which usually equals to several million rows of data. I have also used that data for visuals and tables. Also, for different backends I have not experienced something similar to what you have described.
Where have you created the "success rate" column? In the backend or in Power BI?
DirectQuery does not work with measures and calc. columns in Power BI so far. I guess we will see some improvements there soon, as DirectQuery is the go-to-solution.
// What i recommend: Use other visuals.