I ran into the same problem. I was FlightTrack for years and about 2 weeks ago It would show "no flights available" for every city pair. I started using FlightView Free. It works but it shows a flight and it shows every code share flight number as well, so for one flight at 10:00, it will take up 4-5 lines. Maybe there is a way to turn that "feature" off.

Edit. Just looked at the settings in the app and it allows you to turn off code share flights. Much better now.