I've posted this problem on forge.prestashop.com, but the post was closed with the motivation "cannot reproduce". Now I post an extract hoping that this problem can be solvable. If you see the phase four, I tried to come back to the 0.8 version, but I'm not able to do it. I try to explain step by step what happened.
Phase one: Module (v 0.8) work correctly, but I see that an update is available. I proceed with the update. Now I have version 1.1.0
Phase two: With the new version I try to upload some new banners, but (in Firefox) nothing happen: remains the default image. I try to change the name of image, delete Firefox cache and Prestashop cache. The problem still remain. Then I try with Chrome, but now the personalised images already uploaded are disappeared and in in their place there is an image with a question mark.
Phase three: I try to reset the module. Nothing happen. I try to unistall the module, but the module remain installed. Then I delete the module and now I can reinstall it, but if I try, an error message appear on the top: "themeconfigurator module that you have been uploaded is not a valid module".
Phase four: I upload manually, in the modules folder, the old folder themeconfigurator. Now the module have come back to the 0.8 version, now I see the old personalised banners, but the problem described in phase two still remain.
Phase five: I try to update again the module, but nothing happen: I'm again in the phase two.