Why isn't screen recording working?

I’m running Sonoma on my MacBook Air and screen recording isn’t working. Everything I’ve read online says I should be able to record my screen by typing shift + command + 5. But when I do that, nothing happens. I opened Settings and looked through all the keyboard shortcuts and didn’t see this key combination assigned to any applications. Is there a good way to troubleshoot this problem? Thank you.

In Settings > Keyboard > Keyboard Shortcuts, do you see it assigned here?

No, I don’t see that shortcut. And there isn’t any “+/-” below that would allow me to add it. I’m guessing the next best thing to do would be to click “Restore Defaults”.