I may have solved the problem.
Because those pics were attached to the cart element, I thought about temporary moving the cart elsewhere in the layout (Enfold>Show options>Header shopping cart icon), purging the cache and then putting again the initial cart option.

Apparently, the old urls were cached somewhere by Enfold (the old URLs were in the css as background attributes).
It’s something never happened before, I wonder if someone had ever the same glitch.

Cheers