Why am I not seeing any reply time metrics from my Facebook tickets?
A likely cause is that replies on these tickets were initiated from inside of the Facebook account, instead of the Zendesk interface. The Facebook interface reply does not count as an agent reply. From within a Facebook ticket, an agent's ticket comments still show their avatar and name, while the Facebook interface reply shows the name of the account.
For more information, see our guide on setting up your Facebook channel.