If your SSRS report viewer’s “Loading” popup message never goes away (the report never renders) then chances are you have a reference to an image that does not exist in your report.
I got this because I have a report template that I use for many customers and I like to show the customer’s log with an image with expression like
=Parameters!Customer.Value & ".jpg"
Which then requires that I copy a jpeg file called customername.jpg to my reports folder. If I did not have the logo, which was common for new customers then the logo was just blank but they Microsoft released IE11 and reports without a logo failed to render at all.
I have not found a way to fix this as there is no native IfFileExists() function (reports do not have access to the file system directly).
I tried updating the report viewer control to the latest version and this fixes other issues like the print button not working properly but it does not appear to fix this missing image issue.
You could move the jpegs to another place like a database or create a CLR extension but that’s a bit of overkill for a single browser issue (that shouldn’t be your responsibility to fix).
Workaround is therefore to simply make sure the file exists
The reports render fine in other browsers with the Report Viewer control!
The reports render fine when using SSRS directly without the Report Viewer control. So this is definitely a Report Viewer issue.