Named-checkzone stops silently

[fbsd at www.zefox.net]

I'm setting up a new, non-recursive, authoritative secondary
nameserver using FreeBSD 12.2 and bind9.18.32. It works to the 
extent that runs and answers queries correctly, but attempts to use

bob at pelorus:/usr/local/etc/namedb/slave % named-checkzone -d hosts.zefox.org
loading "hosts.zefox.org" from "-" class "IN"

result in no further output and no return to the shell prompt. 
I expected at least a return to the shell if everything is ok,
as I think it is. 

Apologies if this is, as I suspect, a naive error. I could recognize no
useful clues in the man page. 

Thanks for reading,

bob prohaska