I have a scenario where content is not displayed on W7/IE9 unless I have the F12 development environment open/enabled. I don't have that problem on other browsers (FF, Chrome).
I monitored the traffic not using F12 output, and I do see the response with the content payload. Nothing gets displayed. I hit the browser's refresh button and nothing occurs. I turn on F12 and hit refresh and the content displays.
I saw IE9 makes ajax call correctly only ofter hitting F12 but I don't have any console.log calls in the JavaScript.