Lightbox code is not added to html

i installed featherlight, moved featherlight.yaml 1 folder up, made sure it is enabled and activated, and am now trying to get an image to display with a lightbox link, but it remains a simple image.
![image](/img/img.png?lightbox=600,400&resize=200,200)
turns into
<p><img src="/img/img.png?lightbox=600%2C400&resize=200%2C200" alt="image"></p>
i'm using the antimatter theme, but have tried with twentyfifteen and gravity, too. same same.
does featherlight require something more?

edit: grav is running as a blog, i think i started with the blog skeleton.

i just tried another example from the media section in the documentation and realized that that fails in the same way; so the issue has nothing to do with featherlight!
what else could be wrong? markdown is surely enabled, so is markdown extra, but i tried disabling that temporarily.

"moved featherlight.yaml 1 folder up"

You should move it to user/config/plugins. 99% sure it's not active (you need to enable the plugin and set it to active) and JS/CSS is not added to the page.

what, did my post just get deleted? i don't understand this weird js interface.

anyhow, no, i did all that properly.
and i found a solution:
my dedicated image folder was not a subfolder of pages, but of the webroot.
for some reason grav is still able to display the image, but not able to apply media actions.
putting a symlink to the folder in question inside user/pages solves the issue. sorry for the noise.
thanks again, im amazed how active you are here!

Ah yes, that explains it, the image needs to be under /user/pages as with any user-facing content.