Old issue that has been reported a hundred times. 10 minutes does not mean 10 minutes, it is more like 4 hours and the timer resets EVERY TIME you try to load that page. Honestly, just leave it for several hours. If you need to know if there are slots in a specific hour until then, open a new route page for the airport in question and some random airport and set the departure time to the hour you need info on. Its a pain, but the only work around.