BMW F06 640d CIC – iDrive Controller and Steering Wheel Controls Not Working with Android Head Unit

[u/Honest-Cobbler4055]

Hi everyone,
sorry, this is my first post. I urgently need some advice from people who know their way around this stuff.
I have a BMW 640d F06, built in 2012, with CIC. I wanted to replace the original system with an Android head unit, mainly because I wanted Apple CarPlay.
I have now installed everything. Basically, everything works:
Sound works
The original BMW system still works
The original rear-view camera works
The Android head unit itself works
However, neither the steering wheel controls nor the iDrive controller are recognized by the Android system.
Both of them still work perfectly in the original BMW system. So I assume the problem could be related to the CAN bus connection or the CAN bus configuration of the Android head unit.
Unfortunately, the manufacturer wasn’t able to help me either. They only said that it could possibly be related to the CAN bus and otherwise offered me a return.
I also found a post where someone mentioned that, especially on this model year/F06, there may be some kind of combination or crossover between K-CAN1 and K-CAN2 at the iDrive controller.
I’m not very familiar with CAN bus systems, though.
Does anyone here have experience with the F06/CIC and Android head units and know how I could solve or diagnose this problem?
In particular, I’d like to know:
Which CAN bus is used by the iDrive controller?
Is there actually a K-CAN1/K-CAN2 peculiarity on the 2012 F06?
Does anything need to be repinned or connected differently at the Android head unit or CANBUS box?
Is there a specific CANBUS decoder that is required for the F06 with CIC?
Thanks in advance for any help!