Here are a few screenshots of suspicious behavior:
Light theme displays color palette 1:
Trying to change it doesn’t show “Theme Default” as an option:
Choosing “Light (manual)” (a custom palette I created using the default to try and get a default light palette that didn’t rely on the default) fixes things, but still doesn’t show an option to use the theme default:
In the admin interface, selecting the light palette:
and clicking preview gives a dark-background preview:
-Brad