Ha, my sister had the same issue. I tried creating a tube, but at sunset at a certain time of the year there was no stopping it. Unfortunately, the wires were run behind the drywall, so I had to cut the wires, and swap the emitter and receivers. Curious how your shield was designed, though.
I just accidentally hit this with my foot after years of it working and it broke! It was just designed to be a little hat that had some supports that held it in place around the emitter.
Ah, so the sun was coming it at a higher angle, and a cover that served as a hat brim over the receiver was enough to shield it. My sister's problem was more due to the light coming at sunset low enough that it would have to be a long tube extending a decent amount to try to filter out the sunlight while still allowing enough of the IR signal to make its way to the sensor.
