I just downloaded the applications for Ubuntu Studio. All went well. The problem is that many of the applications such as the installer and Inkscape, the icons and text cannot be seen. I have tried changing themes, and colors. But the issue persist. It is using white or near white text and icons, and so I cannot see the toolbar and items in many applications. Does anyone know what setting I need to change to fix this?

Which exact Plasma version and distribution? -> (System Settings -> System Information)
What Global theme and colors do you use?
Did you check the Gnome/GTK Application Styles? -> (System Settings -> Appearance -> Application Style)