We have LED traffic signals which cannot be seen at low sun angles. The bright morning or evening sun outshines the output of the lamps and makes the signal nearly indistinguishable for east and west facing lights.
I’ve also seen in one case LED traffic lights whose output was so directional that as you pull up to the white “stop” line, you can’t tell which light is on. For some reason there was not another light at a lower angle on the other side of the intersection.