I’ve searched online for an answer to this, but cannot see it has been addressed recently.
I have an iPhone, iPad, Mini and a new MBP running a M1Max.
On my MBP, when I received iMessages, the contact name does not show up. It displays the person’s number. I’m in the UK, so it shows +447…
However, the contact name shows up in the iMessage app and elsewhere on my system, just not in the notification in the top right corner. It’s really bugging me.
Do you have multiple address lists? For example, the majority of my contacts are hosted on Google but I have a handful on iCloud. If both groups aren’t selected in Contacts those names will not show up in iMessage.
I see something similar if I have the contact saved in the contacts app/database without the +44 at the start. For example, if I have a contact saved as 07700 900001 then the person’s name will not always show up, just the number (+44 7700 900001). However, if I edit the contact so that the number is saved as +44 7700 900001 then the person’s contact name shows up.
Having the number saved in the contacts app/database with the +44 at the start (and omitting the initial zero) does not have any affect on making calls within the UK to UK numbers. The phone or network seems to understand that I am in the UK and it is a UK number I am calling.
Not sure of this will fix your issue but this is something I have had to start doing in the last couple of years to see the name of the person who has sent me a text/iMessage.