I’m not sure if that is what I meant when asking if speakers are muted. I mean all speakers.
When you plug the headphone jack in, ALL of your speakers should immediately be muted, with no need to touch the mixer. Does that happen?
If that does not happen, it is a clear sign of an alsa sound driver misconfiguration, and knowing this fact will help narrow down what needs to be investigated.
This is in the alsa documentation.
Knowing that the hardware audio codec is an ALC260, one can then apply a custom model setting to force the alsa sound driver to a specific configuration upon boot (or upon restart of the sound driver). If I look at the alsa documentation (the HD-Audio-Models.txt file) for the ALC260 I note this list of model options that can be forced:
hp HP machines
hp-3013 HP machines (3013-variant)
hp-dc7600 HP DC7600
fujitsu Fujitsu S7020
acer Acer TravelMate
will Will laptops (PB V7900)
replacer Replacer 672V
favorit100 Maxdata Favorit 100XS
basic fixed pin assignment (old default model)
test for testing/debugging purpose, almost all controls can
adjusted. Appearing only when compiled with
auto auto-config reading BIOS (default)
Note that an “hp” or “replacer” option may in fact apply to completely different hardware. Typically the option label only applies to the 1st machine that the alsa developer got this working on.
So lets say you wish to try the model option “hp” and force that upon boot/alsa-driver restart. You would do that by adding a line/changing the /etc/modprobe.d/50-sound.conf file to:
options snd-hda-intel model=hp
options snd slots=snd-hda-intel
# u1Nb.VuErAdw+2mB:82801G (ICH7 Family) High Definition Audio Controller
alias snd-card-0 snd-hda-intel
then restart alsa with su -c ‘rcalsasound restart’ and then restart your mixer and test your sound/headphone behaviour.
If ‘hp’ does not work, try the next item in the list, replacing ‘hp’ in the /etc/modprobe.d/50-sound.conf file with ‘hp-3013’ and restart alsa and restart the mixer and test.
In some cases sound will not work at all even in speakers. In other cases there will be no difference. Try each item in the list until you find one that works, or that you have gone through the entire list.
Even if this works, you are likely in bug reporting terroritory: (1) if it does not work only an alsa developer can help (and openSUSE has an alsa developer who can help) and (2) if it does work, it would help if you would advise the alsa-developer (via a bug report) as to what work, so that they can update alsa to automatically configure your PC for other users.
Before writing a bug report, please advise here, and I can give you guidance that will help you (and the alsa developer) get the most out of the bug report.