 To me this is not a bug. But I'm picky like that. In vFoglight 6.5.1 (Foglight core 5.5.8) any report/view/process that runs longer than 5 minutes are killed by the core Foglight Engine. This is a safety mechanisim to kill "Rogue" process.  I would recommend looking that the vFoglight infrastructure. I have resolved this issue for many clients by tuning the database or vFoglight server for better response. Let's find out why it is taking so long for the report to run. Also if you are using "Generate Report" try scheduling the report. The "Generate Report" option maintains a link between the client and the vFoglight host and the connection may time out. The report may have been generated but your connection to the vFoglight host was lost.  The resolution in vFoglight 6.6 is to show a progress bar with more feed back to the user. I'm not sure if the 5 minute limit has been expanded. So if the underlying infrastructure is having issues the reports may still not work.
Does anyone else have this issue?  I have several reports that when they contain a lot of data, run forever, and I never get the report.
Reports that run "Generating Report. Please wait..." forever