A very common suggestion to a litany of problems is the car battery. I have comfort access and if we leave the car sitting for a week or so, when I come back to the car normal comfort access doesn't work, and I'll need to use the fob buttons.

Not exactly the same, but on the same path at least. Perhaps your car is shutting down the extra features to preserve battery?

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'08 X5 4.8i - 190k
'15 i3 - 95k - Blown AC compressor

'98 323is - 170k - Garaged
'94 325i - 208k - Sold