If your guy did not use a BMW filter your going to have problems when it shifts. A friend had this issue with a E38 7 series. The aftermarket filter would collapse restricting flow. Installed BMW filter fixed it. Most indys will not use BMW parts.

I believe it started happening after the fluid change but he purchased pentosin ATF and an OEM filter. I do remember that he scanned the transmission once before and it came back with something to do with heat.

It's fixed!. It needed a software update and that's all.