This is a common problem on the ZF transmission.

In addition to a fluid drain and fill (I'd avoid a full flush if you're approaching 100k miles) and filter change, there is a software update which can help.

I had my indy shop apply the software update and the hard shift went away. But now the transmission feels like it's in sport mode all the time by holding on to gears longer and I've lost 1 mpg.

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2006 X5 4.4i
Sport package, summer package, cold weather package, DSP + Nav
Bought 2/14 with 73k miles