We are experiencing the same problem on our SnomOne blue. Attended transfer from Snom320 to another Snom320 doesn't update the CallerID.
I have tested the suggested update to 4.5.0.1090 and the additional line in the PnP template but both didn't solve the issue.
Since the CallerID update is a basic pbx feature I would like to solve this issue. Do you have an update on the new firmware?