I have a gallery of 30+ JPGs.
For one of the pictures the thumbnail is not shown.
Instead an icon and the title of the file is visible.
IF I click on the icon then the JPG is shown normally.
I renamed the file and changed it a little bit but it doesn’t help.
The phenome is shown here: www.ti-cons.com/TC2/index.php/en/services-en/men-at-work-en
It’s the last picture.