Why don't I see suggested palettes for my template?
Palettes are only generated for templates with more than one color group.
Suggested palettes need at least two separate color groups in a template to make sense – for example, a background group and a separate accent group. If a template has only one color, or no color controls at all, the Colors tab won't show generated palettes for it.
In that case, you'll still be able to use Presets (template variations made by the author) and adjust colors manually.
This is intentional: with just one color to work with, a palette wouldn't add anything a single color picker doesn't already do.