Just got my 2021 Leon eHybrid and had to struggle with getting my Carlinkit T-Box to work in it. It would not connect at all, i thought the USB-C ports in the car were faulty. Tried to charge my Apple Watch from it and it charged so there must be power. Then i thought the cable im using might not support data. Went to buy a new USB-C cable with highest specs, and still nothing. Then i remember there was a USB-C cable in the box that the Carlinkit came in. Went thru all the cables in my storage (there is many!) and happened to find it. Still nothing!
Then i went inside to think a bit, and thought that maybe it is my iPhone (that is connected to the car via wireless Carplay) that is blocking the Carlinkit from working. Left the phone inside, got in to the car and connected the AI-Box to the usb-port with the original cable provided, and it worked!
So apparently the infotainment system cant handle atleast an iPhone AND a Carlinkit AI box at the same time. Thats wierd, cos my previous Aronan could..