It’s always the small things you overlook…
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…
Looks like it’s working now. Looks a whole lot better with all the images :-)
Edit For existing posts: Edit the post, then Save. (No need to change anything). This also fetches the image.
This is only an issue when you’re using a lemmy.world account. I’m able to skirt this issue for a while by posting through lemm.ee.