Sounds like the circuit breaker built into the switch is getting weak and shutting off the lights. Then it cools and the lights work again. When you hold the stick back for "flash to pass", the lights are powered through a different circuit and the breaker gets a 'rest' which enables it to work again for a while.
Another possibility is that something in the headlight circuit is genuinely drawing too much current and causing this. You could have a defective headlight, but it's probably the breaker.