Most of the time, this issue is usually related to restrictions (operated by the hosting provider) on the server on which the script is hosted. And you can see in the server's PHP errors log this message:
symlink() has been disabled for security reasons.
... or something like that.
In this case, you have to make sure that the PHP symlink() function is enabled on your server. And all images on your website will be displayed (without any additional action on your part).
For information, this PHP function comes with the PHP default configuration and is required by the script to share the images directory in the script's public directory by creating a symbolic link.
So, if the PHP symlink() function is disabled (or doesn't work for some reasons related to your hosting's settings) and if you have a SSH access to your server, you can also create the images symbolic link in command line like this:
ln -s /path/to/storage/app/public/ /path/to/public/storage
Or like this:
cd /path/to/public_html/public/
ln -s ../storage/app/public/ ./storage
NOTE: Don't forget to change /path/to/ by the path to your website root directory.