Based on the screenshots, I suspect that this is a styling issue. As you can see in the div screenshot, the viewer is rendered with 0 height. You may test to compare your page of the viewer with some of our demos with the Html5 Report Viewer which can be found in the installation folder of Telerik Reporting:
C:\Program Files (x86)\Progress\Telerik Reporting <Version>\Examples\CSharp
You can also consider sending us the problematic application, so we can test it on our end.