Update-local-known-hosts on new server producing error

We have a new server we're configuring and for some reason while running the
cchq monolith update-local-known-hosts
command we're getting

[x.x.x.x]: timeout
The following hosts are missing from the known_hosts:
x.x.x.x (monolith)

I was under the impression it would add the necessary entries but it's leaving the existing empty file empty and producing that at the console.
Is there something I should be looking for? The only thing we don't yet have configured is the FQDN - we're using IP addresses in lieu of until that is set up and will update-config later.

Thanks in advance! :+1:t5: