By laserneedle...
The Bowden cables connecting the outer door handles to the latch assemblies may get water inside the outer sheath of the cable. If the temperature drops below freezing before the water dries out, the water may freeze, preventing the movement of the inner cable.

There is a BMW service bulletin for this. It's a really common problem.

Not sure if this it.

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Mike F
Current: 2017 Grand Cherokee HEMI
2017 Kawasaki ZX-14r
2017 Harley RG Ultra
2017 Harley Fatboy S