T46G name display

[steady]

My client has T46G handsets. Remote phone book is setup to 3CX and seems to be working fine.

When I call the client from a number in their directory, they only see the number of the caller on the handset screen. However, if I browse the web interface of the phone, the name is shown:

e.g.

Web interface (received calls list) : Primary Ring Group: ABC Corp
On handset screen: Primary Ring Group: 55151234

So name lookup appears to be working but just not displaying on the screen.

Does anyone have any suggestions?