Are you using a custom theme?
If you add a Feature block to the page, can you see the icon?
Thanks for your reply. Yes I am using a custom theme. And I CAN see the icon of an added Feature Block. Any ideas further? Thanks!
Are you using Font Awesome in your theme?
Are you registering your theme assets in page_theme.php?
I will pass on your last remark to the developper of the theme