one light, two switches
We've lived in our house for 13 years (a 40 year old house) and this has been a strange thing that happens every few months or so. In our laundry room we have a light, it is controlled by a switch in the garage and one switch in our house in the hall. On occasion when the light switch is flipped in the hall to turn that light on, the light doesn't go on. If I then flip the switch in the garage it does go on and then there won't be any issues with it again for months. It's always the same switch that will not turn it on, but once the garage one is flipped it works. The switch in the garage is closest to the main panel, not sure if that makes a difference.