TFT, Nav6, iPhone and Cardo linking

Hi all - looking for help if anyone can.

GSA850, TFT updated few weeks ago. Cardo Packtalk, BMW Nav 6, iPhone XR. If I connect up as per usual recommended method the voice control on the Packtalk works mostly but will not stop/start music (stored on card on Nav 6) and the ‘Hey Siri’ voice instruction is not recognised at all.
Also I can make calls but cannot answer with voice control. If I take the TFT out of the loop and connect headset to Phone and Nav, and phone to Nav all voice control works as does voice control for accepting calls.

Is this usual - if so I'm not quite sure what advantages including the TFT in the link up is going to bring? Can anyone advise?

Hi try a FB page BMW TFT connectivity and try the VT that’s at head of it should help with pairing procedure and operation

Good luck

This is the ‘usual recommended method’ I referred to above.
What I’m struggling with is exactly what is gained by including the TFT in the setup when it appears that it is impossible to retain full voice control functionality when the phone is connected to headset via TFT.