Because it is a clipping group (for no visible reason). Release the Clipping Mask or edit contents.
Open the Layers panel and you will see a clipping group.
Because the Draw Inside mode creates a clipping group with the option to edit the content. In your case you already created a clipping group.
Thanks for the help.
Good to hear that helped.
It's just the mask. There's nothing in the mask.
That's it there is no reason for it to be a mask, it would look the same as just a filled shape.