Sequoia screensaver stuck in Automatic

Just upgraded to Sequoia 15.1.1 and trying to set my screensaver to the new Sequoia one. However, I can't get it out of Automatic mode. Whenever I choose either Light or Dark in the dropdown, the preview icon changes, but the dropdown still shows Automatic is selected, and that's what shows up when the screensaver is previewed or comes on due to inactivity.

My understanding is that Automatic should be dynamic when appearance is Light/Automatic and Dark when appearance is Dark, but I would still expect to be able to manually set the screensaver to either permanently Light or permanently Dark regardless of appearance settings. I tested this just now at 10 a.m. when the dynamic screensaver has purple in it, to distinguish it from both Light (blue/orange) and Dark (all blue) modes. What actually happens is this:

When appearance is set to Light or Automatic, the screensaver always has purple in it. I can't manually set the screensaver to either Light or Dark.

When appearance is set to Dark, the screensaver is always Dark. I can't manually set the screensaver to Light, and although setting it to Dark wouldn't change its appearance, attempting to set it to Dark and then switching macOS's appearance to Light results in a dynamic screensaver with purple in it. So the screensaver clearly wasn't actually set to Dark at all.