X5 E70 transmission woes

[Dieseldonkey]

Hi guys,
2010 BMW X5 diesel (E70)

135,000 miles original transmission fluid and no visible leaks

Noticed that on occasion when switching the shift knob from park to reverse the x5 will make a rough bang lurch and switches to park automatically.

From research, I have not found out what is the cause. One thread noticed if a door or hatch was open the car would throw itself into park.

I'm debating if now since the x5 is having issues that I will get the dealer or myself to change the transmission fluid+filter and see if this helps the problem.

My thinking is the transmission could be low on fluid?
Valve body?
GA6HP26Z is this the transmission in my e70?

Any ideas?

Thank you kindly