And when I click, or right click, on the single image (thumbnail or colored rectangle) the link doesn't work.

if images are slow to load don't sshow at all when search on google image, tye the flowing try private browsing mode clear your cache &cookies turn off any toolbars & exxtensions turn on javaScript

If each steps are do not working post about your issue in the Google.Search Forum

In browsing mode images do load correctly. I have no toolbars nor extension installed.

Loading images in Google search still doesn't work. I try to do a clean installation of Firefox but the problem remains. Any suggestion?

To include a picture in Google search results, add your image to a website along with a description. While you can't directly upload images into search results, searchable images posted on a website can show up in our search results.

Dinushi Dhananjani said

if images are slow to load don't sshow at all when search on google image, tye the flowing try private browsing mode clear your cache &cookies turn off any toolbars & exxtensions turn on javaScript If each steps are do not working post about your issue in the Google.Search Forum

A certain and simpler method, for me at least a former Bell Telephone Laboratories Autovon programmer, is to click another Browser's Icon on the bottom of my screen.