This is almost always due to switched hot wire and neutral at the timer or before the timer. Or possibly a dosgy timer which bleeds thru a bit of current, enough to feed the driver to a low low operation. l If your plugs are reversible then try that. If not reversible you need to make sure that the those pins kinda get reversed. If you dont wanna mess with your installation or light just yet you can try getting a small extension cord, cut it in half and reconnect the cables but live nd neutral reversed (usually this would be blue and brown wires in your cable. Put the timer after the jimmied cord and try again. If no joy then there is probably something wrong with the timer or figure where the light can draw a low ac current from. But its almost always as simple as reversing the cables or turning your timer 180 degrees around