I recently noticed an issue on a UC560 (running 15.0XA2) with the transfer-system set to full-blind.
When initiating a transfer on a SPA525G phone, the caller ID information on the display changes to "Anonymous." This happens immediately upon pressing the Transfer softkey, and seems to be happening with all calls. Once the transfer is completed, the information reappears correctly on the recipient phone.
This seems to be impacting only SPA525G phones (first noticed the issue on 7.4.3, and persists on 7.4.4). The problem does not occur on other SPA502G/SPA504G phones on the system (the caller ID is retained on the display until the transfer is completed on these phones).