Last week I had my bike prepped for winter by All Year Biker using ACF-50. The same evening I took the bike out for a nighttime run. As I entered unlit roads I flicked the lights to main beam, and there was nothing but total darkness (even the main beam warning light in the instrument panel was dark). For the rest of the ride the dip beams worked fine but there wasn't a glimmer from the main beams until I used the headlamp flasher, which immediately lit up both main beams as normal. From then on both the main and dipped headlamps worked normally.
The weather was dry but cold, and there have been no previous problems with the lighting.
Can anyone give me a clue as to what the problem might have been?