This happened to my X5. I could use existing paired phones but could not get into pairing mode. It turned out to be the wiring at the TCU that BMW had to fix.

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2011 550xi Carbon Black/Oyster, M-Sport, Premium Package, Technology Package, Electronic Damper Control, Dynamic Drive, Comfort Access, Active Seats, Surround Cameras

2013 X5 5.0 Space Grey/Black, M-Sport, Premium Package, Technology Package, Comfort Access, Surround Cameras