Colormag free Facebook sharing issues

I installed the free version of Colormag and I am very happy with its features: speed, configurable, good design and widgets.
The problem I have now is that I tried to share the homepage url (https://argencello.com.ar) with facebook, and it keeps showing a blank square and it says: Untitled Document.
I have installed and perfectly configured Yoast SEO plugin, with all the Facebook data I could introduce (app id, admin, admin id, open graph on, default image, etc,) with no results.
When I share the URL with the index.php part, or I share another post or page, It shows correctly.
It’s weird that in Google+ or Twitter the link is showing perfectly, with images, site title, all. It’s only a Facebook issue.
I have configured colormag NOT showing static page, as it says in its configuration guide: https://themegrill.com/theme-instruction/colormag/
I checked’Check to hide blog posts/static page on front page’.
I followed all steps of this guide, the site looks good, just this FB problem. I use a lot Facebook to promote my site, and I need that well configured.
Could someone help on this?
My site (again) https://argencello.com.ar