Speed Dial doesn't find all my Contacts

I paired my iPhone with the Bluetooth function in my new PIP, but did not load all my Contacts into the car's system, as I have more than 2000. I just wanted the car's system to access my phone's Contacts via Bluetooth.

But ... when setting up Speed Dials, many of my Contacts show up on the screen as candidates for speed dial registration, but not all. Including several that I want to register. Is this because I have so many Contacts? And is there a way I can force the car to find the ones I want to register as speed dials?

Thanks in advance ...