I have the same problem. When I load your example project, all is fine. But I noticed that your example project is set to “Desktop” - “CMake/Eclipse/…”. I am working on a project with “Arduino” - “Giga R1…”. When I change your example project to match mine (“Arduino” - “Giga R1…”), your example project exhibits the same failure in not honoring the Checked - Style (Button Items) settings to adjust the selected tab styles. This seems to be a bug when using the Arduino Giga R1 setting for the project.