KDE apps such as kwrite and okular do not find the network printer.
GTK apps such as LO and firefox do find the network printer.
Using CUPS web interface to set the network printer as the "server default" makes KDE apps aware of the network printer and enables printing using those apps.
While that is an acceptable workaround when only a single network printer is available, it may not be adequate when the user has several network printers.
I think that this looks like a plasma/KDE bug and not a CUPS bug, but I've no idea which package is responsible.
IIRC the bug has existed since I upgraded from Mageia 5 to Mageia 6 on 17th July. I am reporting it now because it seems to be affecting at least one other user:
I can confirm the bug and the work-around.
I have 2 printers on the same server (MGA5 install) and I can see and print to both of them after setting one to serer default.
Seems to be this:
So perhaps a cups issue and not a KDE issue
I confirm the bug also.
it's impossible to print on a CUPS/network printer from any QT/kde applications (gwenview, okular ..), but it works fine from gtk based apps like firefox.
It seems to be a bug related to cups 2.2.4, it affects also archlinux users (see https://bugs.archlinux.org/task/54695).
I found a solution :
I recompiled cups 2.2.6 from cauldron SRPMS (ftp://distrib-coffee.ipsl.jussieu.fr/pub/linux/Mageia/distrib/cauldron/SRPMS/core/release/cups-2.2.6-1.mga7.src.rpm), and now everything works as expected, I can use my cups printers from any applications (QT/KDE/GTK).
Fixed in cups-2.2.6