I am using for some time this ppa and the mentioned package
I observe that in both 22.04 and 22.10 there are two icons missing in Control Center...
Hope maybe @lah7 or someone might fix this issue.
I love this Theme, and I don't intend to move from this theme in the feature, only if it remain unmaintained, and it brakes.
Ah yes, I also encountered that.
Here are my $0.02
I use this icon for 'indicators'
/usr/share/icons/hicolor/scalable/apps/ayatana-settings.svg
I use this icon for 'Mate Tweak':
/usr/share/icons/menta/256x256/apps/background.png
I remember that I had to spend some time to find suitable icons.
I also love this theme and I will keep it on my systems as long as i can.
I do not have write access to the PPA but I am prepared to help out any way I can to keep this theme from dying.
I hear you! I don't daily drive Ubuntu MATE or the theme/icons myself, so I'll need to be notified whenever something breaks. Ideally by creating an issue on the Git repository. Even better, create a pull request.
I made the fixes:
.desktop file in /usr/share/applications hardcodes the icon to /usr/share/icons/hicolor/scalable/apps/ayatana-settings.svg, but for whatever reason, the one in MATE Control Centre expects an icon named system-component-addon.Published a new 22.04.1 release, the PPA will follow shortly.
Since I kept the desktopfiles, that i changed, in $HOME/.local/share/applications
(which actually works) I never noticed that.
But for this cause, I just deleted them and made the changes in /usr/share/applications and indeed it doesn't follow the settings in ayatana-settings.desktop
It is, however, not hardcoded:
Tracing links back and forth, I discovered there is another .desktop file: /usr/share/mate/applications/ayatana-settings.desktop which indeed has the line Icon=system-component-addon
If the patch is made against /usr/share/mate/applications/ayatana-settings.desktop instead of /usr/share/applications/ayatana-settings.desktop I bet there is a high probability that it will work 
Sorry that I can't send you a pull-request (I don't have a github account, and to be honest I don't even know how it works 
) but I hope you can do something with this info.
EDIT: Changing that desktopfile will probably damage other themes so I guess that the Ambiant-MATE icon theme needs a copy of (or softlink to) ayatana-settings.svg named system-component-addon.svg or something like that
Good find! Thanks for the info. I'm a little rusty with MATE, but did vaguely suspect something somewhere was different for MATE Control Centre (which I never really used). If I recall, the icon in the System → Preferences icon is broken too.
I did add system-component-addon to the categories/scalable folder, but in hindsight it might need to be apps/scalable instead.
While symlinking is possible, it's bad practice for the theme to be making links outside our own theme. It seems every non-Yaru theme is broken. 
Yes indeed, it also contains the line Icon=system-component-addon
But it is, as far as I can tell, not a seperate desktopfile, it is merely a link.
When I removed my local version of the desktop file, the icon in both control-center and system -> Preferences disappeared.
So it is either patching Yaru to be compatible with the rest or patching everything else to be compatible with Yaru or a case dependent workaround. This could be getting messy real fast. Not a pretty sight.
P.S. I don't know if you have Ubuntu-MATE running but if you don't I am fully prepared to test stuff for you if needed.
The only thing that I may have got wrong is that it may need to go in "32" instead of "scalable". It's been a while since I've dealt with icon themes. Pretty sure there may be a cache to deal with as well.
In /usr/share/icons/Ambiant-MATE/categories/, you could try moving it out of scalable and into 32 instead (as root). I can see that Yaru put this named icon inside categories, so my previous comment about maybe needing to be in apps is incorrect.
system-component-addon isn't in the XDG standard. That said, Ambiant-MATE is already a mess with symlinks for what I presume was to support the old days of apps using non-standard icon names. 
I only have Ubuntu MATE in a VM, but I'm focused on other things at the moment. I think a more proper fix is to change this MATE-specific ayatana-settings file so it uses the same icon as the /usr/share/applications version, so it's fixed for all themes. This command will tell which package installed this file:
dpkg -S /usr/share/mate/applications/ayatana-settings.desktop
If that works locally, then raising a bug on Launchpad should reach the right person. 
Thanks 
Bug reported
Thanks guys,
You both are so amazing,
Just update the system and observe both packages have an update, and after update, check one icon fixed... marvelous