Solved CUPS in FreeBSD 11.0: printers are not listed

When I started using FreeBSD 11 a year ago, print/cups worked perfectly. However, after a certain update (it's happened to me at r298793) my printers have disappeared from the list in LibreOffice, Firefox, GIMP and others, but I was able to print from graphics/xpdf using /usr/local/bin/lp using as a print command.

That time (May 14, 2016) I started a fruitless conversation on the mailing list.

Now FreeBSD 11.0 is practically released, but print/cups still behaves the same way. Am I missing something?

Thanks for ideas!
I've found the solution by reading this 6-year old topic!
The funny thing is that it was suggested to use a line which became the culprit in my case!
Port 631
Probably I've added it long time ago for the same reason, and eventually it's become obsolete and harmful. The fresh cupsd.conf.sample in FreeBSD 11.0 comes without it - having only:
Listen localhost:631
Listen /var/run/cups.sock