I’m unable to add icons to my toolbars on the latest version… any news?
Yes. You have a plugin installed that is causing a conflict. Likely Selection Toys or 1001 Bit Tools.
Disable them. Restart SketchUp. Organize your toolbar.
This is a known issue triggered by certain extensions, particularly selection toys and 1001bit. Try removing these if you have them, restart SketchUp and see if that cures it. You can reinstall the extensions afterward if you are finished customizing.
There may be a fix in the next SketchUp update…stay tuned.