W3TC crashed subdomain theme in WP multisite

Hello,
After sucessfully going ahead throughout all the process of installing WP multisite (subdomain install + WPMU domain mapping) I have unexpectedly crashed (probably) into the W3TC plugin. If the W3TC plugin is disable, everything looks ok. As far as the plugin is enable, then CSS seems to crash only in my subdomain site (http://www.pico-sa.pl) while the main domain (http://www.aitana.pl) remains OK.
I provide below with the more relevant information:
1/ Both sites have exactly the same W3TC settings in order to avoid any .htaccess conflicts.
2/ W3TC is not working as network but configured individually for every single site as recommended.
3/ First I created the main site (installing W3TC and many other plugins) and as soon as the main site run well I decided to go ahead with WP Multisite installation. So the W3TC plugin was installed before WP Multisite installation proces.
4/ I am using the same Genesis theme (outreach pro) in both sites
5/ Everything looks as it works (WP multisite dashboard funtions, theme, ..)
6/ It appeared the following sentence on my WP dashboard: “Recently an error occurred while creating the CSS / JS minify cache: No sources to serve.”
I have spent almost 2 days looking for information about wp multisite configuration + w3tc. I appreciate very much any suggestion or comments on where to find information about.
Uninstalling W3TC is hard and I would ilke to try first if there is any possibility to set this.
Thanks a lot
Fernando

https://wordpress.org/plugins/w3-total-cache/