iussue with the Product Attributes drop-down menu on shop page

[Enter Prestashop]

My prestashop istallation is1.7.5 and i have products with multiple combinations. Selecting any of them would be only temporarily for a second before switching automatically back to default. The changes I did before that happened were:

• install and activate one fo those plugins that creates clean URLs;
• update the configuration of the SEO friendly URLs in the SEO and URLs backoffice section;
• Installed a module that allows me to create combinations with virtual products

I activated debug modality with friendly url and i fouded this error on override/classes/Link.php.

If i disable override, combinations switching back to default.

Any suggestion?