The problem is with your nginx
rewrite rules. I have already setup and tested X3 successfully on NGINX with these rules:
https://gist.github.com/mjau-mjau/6dc19 ... e566a8457b
More specifically, there is a rule:
rewrite ^/render/. /app/parsers/slir/ last;
The above will rewrite requests for resized images to the X3 image resizer (which is not working in your screenshots above). For example /render/w320/path/image.jpg will rewrite to X3 /app/parsers/slir/?, which then resizes and serves the image. Once the image is created, it will exist in that path, and the rewrite rule will no longer apply.
I have had a couple of users with the same issue, and the problem was that they had conflicting rules in their nginx config. For example some rule that triggers on *.jpg, which then causes the above rule to be ignored. If the rewrite rule is ignored, it means nginx will simply not find the file and report "404 file not found.".