The ISO is correctly built with Elemental, so there's no problem there.
Then I start the built ISO on the machine I want to install Harvester on and access the shell. Harvester also uses Elemental to install on a target disk with a COS file and a cloud-init. Everything works but at the "extracting file run.sh to /usr/local/tmp" stage, it hangs. Unfortunately, I don't have any more logs to provide. Here's a screenshot to complete the picture.