I have some PBI books that I have scheduled to refresh the imported data on the Report Server - the queries are quite large and take about 10 minutes to run, but the problem is that when the refresh starts running, the report page goes blank. By blank I mean that not even the loading icon is showing, none of the report page shows, it is a blank space where the report page should be, no page outline, no empty graph outlines or data display errors, just purely the site toolbars above a blank site background space.
Once the refresh is finished the report shows again. But considering that the queries run every 30 minutes, that's 1/3rd of the time where we can't use the reports which is very problematic.
Does anyone know why this is happening and what I can do to fix it? It only started happening recently and I haven't changed anything in the reports nor on the server. I'm using the latest March 2018 RS version and have long ago installed the latest file that came out end of April.