[RKN GLA]

Is the car recognizing a device is connected? If not, connection may be poor either with the cable used or the USB plug itself. Try restarting the phone, then a new cable, then checking the USB ports.

Avoid Engineering Mode if possible, when other members have tried changing things there, it has required dealer reprogramming.

 

[RKN GLA]

The funny thing is that when I use the same cable and my iPhone and plug it into my wife’s Suzuki S Cross it the phone instantly recognises her vehicle, but although I see my MB Bluetooth it will not recognise my GLA45.

Bluetooth also doesn't recognize it? What kind of iPhone are you using and is it fully updated to latest software? Furthermore, has the CarPlay itself been activated on the vehicle? I know some of the early CarPlay vehicles only had CarPlay "preparation" (all necessities for CarPlay are there, the dealership just needs to activate it).

you can check if the CarPlay is activated by pressing the "Media" button on the head unit, and then press it again so the "carousel" menu appears. Scroll through the sources and check if CarPlay is there as an option.

 

[RKN GLA]

My iPhone 11 ProMax has latest upgrades.My phone recognises my MB Bluetooth. According to my VIN data
I have.
16U SMARTPHONE INTEGRATION CARPLAY
14U MARTPHONE INTEGRATION PACKAGE
I have no CarPlay option on any of the carousels

You will need to get your CarPlay activated then. That is why it is not connecting. See this thread for more info. Activate Carplay & Android Auto

Maybe your dealer can do it free of charge since the option was already purchased? Best to call and ask.