Never had that problem, but also never nite ride when it's below freezing.Also, the light n motion stuff auto dims in the cold after like 20min IME. Im never buying another.
Light n Motion has been the brand I've used for many hundreds of hours. A few different ones on the helmet, and a few different Secas on the bars. Always solid and zero issues in my experience. I busted the glass lens in one of the small helmet lights, and they gave me a new light FOC, great customer service.
There was a standing Thursday night ride for many years back in NorCal, usually in the redwoods where it is DARK and often wet in the winter. I have tried quite a few brands out over the years. Seen more than a few Magic Shines shit the bed....