media library grid view only one blank gray thumbnails

I’ve have a problem in the Image Library. In grid view (and not in list view) there is only a blank gray thumbnails. If I click one, If I set the list view I have all my images and also I can see on front page, but if I try insert an image in post or page I can’t because library offers only grid view metod to chose it. If I try insert a new image I’ve this error… There is an error during upload (I have italian version so maybe translation isn’t not correct)
https://www.shapewebdesign.it/cu20/wp-content/uploads/2019/09/Screenshot_2019-09-10-Personalizza-Soluzioni-IoT-e-Industria-4-0-per-automazione-industriale-CustoM-2-0.png
This was happening in last upgrade to WP 5.2.3

The page I need help with: [log in to see the link]