The stock not changing, and status still pending.

Still something can be blocking the MercadoPago requests, check your access.log for the MercadoPago requests.
And check if you are using ModSecurity, CloudFlare or a security plugin blocking user-agents (you can check your .htaccess file for it, happens a lot of some plugin blocking the MercadoPago user-agent).

Really not. I’ve wrote to my hosting provider, and said me they’re not blocking the Mercadopago URL’s. I’m not using any user agent or making changes on htaccess at all.
This is my htaccess:

# Do not remove this line or mod_rewrite rules and search engine friendly URLs will stop working
RewriteBase /

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>

# END WordPress

I check all my plugins and there is not User Agent plugins.
Another idea? Many thanks.

Try with the host again, since if not is blocking the status need to change automatically.
And from your .htaccess, looks like your host uses mod_rewrite. It’s not common to have references about it if are not using.

I figure it out some errors on php-error.log file:

PHP Fatal error: Call to a member function add() on a non-object in /public_html/wp-content/plugins/woocommerce-mercadopago/includes/class-wc-mercadopago-gateway.php on line 496

Maybe some is wrong?

Maybe is the debug mode? I find this thread:Debug Mode

Ohh, you are right, thanks for let me know about it.
Fixed in version 2.0.6.

Thanks! Everything works as it should.

Thanks ??