I see this is an old post, but having last month replaced my door actuators and having got back up to 3 out of 4 doors unlocking at the press of a button (yippee!), this month (perhaps hastened by the cold weather?) has brought the failure you describe.. (boo!)

It still unlocks from the (recently fixed) keyfob, but not the button on the upper half of the hatch.

Looks like I'll be buying a new switch panel.
I also noticed that the rattle I've noticed recently might be coming from my lower half of the tailgate, where only one side seems to 'latch'..

Ho hum..

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2000/12 BMW X5 3.0L
1989/12 BMW 325ic
2000 BMW E39 528i