zone-purge not logged properly

I've observed a logging issue with Knot 3.1.4. Here's a sequence:

# kjournalprint /var/lib/knot/journal -z
.
0.a.2.ip6.arpa.
ug.
ripe.net.

# edit knot.conf and remove 0.a.2.ip6.arpa, ug and ripe.net from the config
# knotc reload

# kjournalprint /var/lib/knot/journal -z
.
0.a.2.ip6.arpa.
ug.
ripe.net.

# knotc -f zone-purge 0.a.2.ip6.arpa. ug. ripe.net. +orphan
OK
# kjournalprint /var/lib/knot/journal -z
.

All the 3 zones I specified have been purged. However, in the log, I see:

2021-12-04T11:48:04+0000 info: [0.a.2.ip6.arpa.] control, received command 'zone-purge'

So the logging only suggests the purge of one zone. The other 2 zones were not logged.