This was fixed on lemmy.wtf
a while ago but apparently this was still an issue on lemmy.world
which now has been fixed:
https://lemmy.world/post/1421693
The
docker-compose.yml
I copied from somewhere when setting up lemmy.world apparently was missing the external network for the pictrs container.. So pictrs was working, as long as it got the images via Lemmy. Getting the images via URL didn't work...
Note: This only fixes new posts. In order to fix old posts you need to edit/save them once.