Have you published your Power BI report to the service, refresh the data, and the visuals go blank? Patrick may have an answer for you.
Here you can find information regarding different scenarios you may face when refreshing data within the Power BI service.
When you load data into Power BI Desktop, it will attempt to convert the data type of the source column into a data type that better supports more efficient storage, calculations, and data visualization. For example, if a column of values you import from Excel has no fractional values, Power BI Desktop will convert the entire column of data to a Whole Number data type, which is better suited for storing integers.
Power BI enables you to go from data to insight to action quickly, yet you must make sure the data in your Power BI reports and dashboards is recent. Knowing how to refresh the data is often critical in delivering accurate results.