Created attachment 111858 [details]
Screen recording depicting the issue

This issue was discovered during Kubuntu 18.04 beta testing, and I as well as several others were all able to reproduce it.


Steps to reproduce:
1. Install Kubuntu 18.04 beta or nightly, or boot into a live session (http://cdimage.ubuntu.com/kubuntu/daily-live/current/)
2. Open System Settings
3. make the window wide such that the subcategory list will be visible
4. Click on Workspace Theme
4. Then click on Application Style

The first item in the subcategory list has no selection color and no text color. It appears invisible save for the icon. You can still navigate there, it just doesn't look like it.

Screen recording attached.


Reproducibility:
- Unable to reproduce in Kubuntu 17.10 with Plasma 5.12.4 from the Kubuntu backports PPA
- Reproduces for other subcategory lists, too. The first one you click on looks fine, then any subsequent ones exhibit the bug.
- The colors return if you click on a main category list bold header.
- Reproduces with all look-and-feel packages shipped on the live ISO (Breeze, Breeze Dark, and Kubuntu).
- Reproduces with all color schemes.