Pulseaudio no longer sets the speaker balance on startup
I recently upgraded from opensuse 42.3 to opensuse 15.1. Since the upgrade, I've found that the balance between my computer's speakers is usually not set correctly (so one speaker is much louder than the other) after booting up from power off. pavucontrol shows the correct even balance levels (rather than the incorrect levels that the speakers are currently set to). If I nudge the balance control in pavucontrol a little, the balance is then set to whatever levels are shown.
According to yast, the version of pulseaudio I'm currently using is 11.1-lp151.5.3. I'm not certain, but I think the old version of pulseaudio that apparently didn't have this bug is 9.0-8.1 (determined by looking at the filename in the opensuse 42.3 update repository). So my first guess would be that this balance problem is the result of a bug in pulseaudio introduced between 9.0 and 11.1.
According to pavucontrol, my sound card is a "5880B / Creative Labs CT5880 (Creative CT 4810 [Sound Blaster AudioPCI 128])".
I am not knowledgeable about pulseaudio and Linux sound in general, so I'm not certain that the component with the bug is pulseaudio. If you think this bug is in some other component, please let me know so I can report it correctly. I have not tried to isolate the component that is causing the problem; with the opensuse distribution upgrade, presumably every component of my system software has been updated.