[PS 1.6.1.12] question mark on product images only with user log in

[skara]

The problem in subject appears after log in in FO. The question mark is only for product images including all thumbnails. The other images are ok. 

 

I've tried with Chrome, IE and Firefox with the same results. I've tried to clear the PS cache in BO Advanced Parameters - Performance.

 

Thank you in advance for any help.

 

Some system infos:

 

PrestaShop version 1.6.1.12

Shop URL http://bbhands.com/

Current theme in use default-bootstrap

Server software version Apache

PHP version 7.0.21

Memory limit 512M

MySQL version 5.6.34

 

In Advanced Parameters - Configuration there the warning below, that I don't think is relevant, anyway here there are:

 

 LIST OF CHANGED FILES

Changed/missing files have been detected.

Missing files (1)

• admin123/autoupgrade/index.php

Updated files (1)

• admin123/autoupgrade/backup/index.php