Your test of where you have to have the remote to get responses shows that the sensor is behind the screen. That puts it much further from an external IR emitter than normal. Maybe an emitter on the front of the screen needs to put out way more IR than normal. Plus, maybe that IR emitter isn't working.
Test it with another component to be sure it emits IR. If it does, it could be that the amount it puts out will not work further than a couple of inches from the sensor, so a sensor behind the screen would not see it.
A good answer is easier with a clear question giving the make and model of everything. "The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw
