No, phonebook is not working (can't be provisioned). You can create a custom Panasonic phonebook (upto 500 entries) and upload it manually in KX-UT phones. I haven't tested with KX-HDV series.
KX-UT templates were available for a short period during v11 or v12, after that were dismissed. I have maintained them and upgraded to v15.5, as I have a very large installed base of KX-UT phones. Here are mines -- change file extension to .xml, before uploading into 3CX:
Link up your team and customers Phone System Live Chat Video Conferencing
Hosted or Self-managed. Up to 10 users free forever. No credit card. Try risk free.
Check your inbox!
We’ve sent you an email. Click on the button in the email body to verify your email address – (if you can not find it, check your spam folder).
Upon verification you will be directed to the 3CX setup wizard.