Your unique table is not validated because none of the fields are saved.
So makes your component empty and no screen layout is generated.
On every field, type 'enter' or the 'save' icon. (floppy disk)
For the moment there is no validator that explains you this, but it is on the road map.
I mean, in the builder, when you want to run or download, the project validator will stop you and open the table / layout / brick of the concerned error... So, a bit long to realize for the moment.
Actually, the politic is that your component can ALWAYS be executed, even if something is incomplete.
It will be ignored, so you think it is an issue.