When creating a Superflat world using the preset "Overworld", Strongholds are not generated. again... (MC-131749)

Perhaps this is a removed feature to Minecraft as of 1.16.1 as the generator customization flags are no longer shown when selecting (as example) "Overworld" preset?

But I believe this to be a bug instead. Despite the values missing from the text box, the world will generate with features, trees, lakes, underground lakes, and even abandoned mineshafts.

The various features and structures (except for strongholds) for each preset all work even with modification to block type and layer thickness, despite having no visual indication that they are present or enabled.