UI customization only applies if the user is using the default platform theme.
@if (getCurrentThemeName() !== getDefaultThemeName()) {
You can't preview the changes because you aren't using your platform's default theme.
Current theme: {{ getCurrentThemeLabel() }}
Platform theme: {{ getDefaultThemeLabel() }}.
} @else {
You can preview your UI customization but don't forget to save your changes once you are happy with the results.
}