When we have report action or drilldown or sub report which is rendered in SharePoint 2010 using SSRS report viewer web part you will run into issues that the report is not rendering after the first page load. This is caused by the Debug="True" in the compilation tag in web.config file. In our environment the report was working fine until we made this change in web.config for some other debugging. But we haven’t noticed that this has broke our report and since we had backup of all the web.config changes we were able nail this issue to debug property. Apparently we are able to find that there is a fix from MS based on the below msdn thread. Refer the blow link for more information,
http://social.msdn.microsoft.com/Forums/en-US/sharepoint2010general/thread/1329b784-d050-4d17-bb5d-f42853f420fc/
