managed-keys.bind sometimes stops being updated

[Chris Thompson]

With a managed-keys statement including keys for "." and for
"dlv.isc.org", the managed-keys.bind file is normally updated
every hour for "dlv.isc.org" and every day for "." (the
respective TTLs of their DNSKEY RRsets, presumably). But
sometimes this updating simply stops completely, until
BIND is restarted. The trust anchors go on being used OK,
and "rndc secroots" still shows them as "managed".

The effect seems to be associated with having used 
"rndc reconfig", and I have observed it with both 9.7.1-P2
and 9.7.2-P2. Is this a known problem? Has anyone else
observed it?

-- 
Chris Thompson
Email: cet1 at cam.ac.uk