Owch, have you contacted support?
We have MV72 installed and they have been in -5 Celsius without any issues however they are installed under a soffit.
Are they installed in a place where rain can get them directly? Not that it should matter as they are IP67 rated.
Did you follow these installation instructions?
https://www.youtube.com/watch?v=Hp1-G7OwxC4
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