Configuration time wrong after hotfix upgrade

Hi, We are running a pair of 4200 series on 11.3, and have recently upgraded to HF6. Since the upgrade, I've noticed that the "Configuration time" always defaults to PST (GMT -8). We're in GMT +0 (the timezone on the device is set to Europe/London) so this is pretty confusing. The log files (ie /var/log/ltm) have the correct timestamp, as do the time/date reading at the top of the configuration page, on the dashboard etc.

To make matters even weirder, I've compared this with our F5s at our test site - these are 2900s running the exact same software levels (11.3, HF6), and the timestamp always displays in the correct timezone.

Any ideas?