While we appreciate you taking the time to open an issue, we also would appreciate if was the case to open it … and that was the wrong place to do it. Is unrelated to Gnumeric … and also is unrelated to Manjaro.
Take a look at your default theme in Settings > Appearance > Style and also take a look at the default icons. If you are using a dark theme, then use the dark icons. With Adwaita-dark that you use, then the icons have to be the dark version … It works even with the default Gnome icons.
To know exactly which forum to open an issue is based on experience.
I desperately wanted this resolved; therefore started with the forum where the software belonged. Once correctly explained the situation and given directions to the correct forum, came here.
Good to know that it is not Manjaro’s fault either and I’m excited to get this solved since I’m going to pound Gnumeric daily from now on.