Gmail: pictures not shown in email


is there any known issue with Gmail and pictures not showing? I uploaded my images from my hard disc to Ghost (embedded them into the post), but only the captions are shown on and via Outlook and when viewing it in the browser. I’m self-hosting via DigitalOcean and the picture link works when inserted into the browser url bar. Any help is appreciated.

Site name is
Example image url:
Ghost version: latest