OK, fine.
Now the issue of the “featured” post in the Homepage is solved.
It seems it saved it wrongly (I received an error 503 right after saving).
So I had to put it in another category and in “degression” style, and then go back to the “featured” category and “standard” blog post format.
That said, in the “Blog” webpage is still missing the last three articles, inexplicably.
I will try to save them in another category and go back.
Updates soon. ??