It is solved, there was a mismatch between the configured device name and the actual device name between the different tests.
cmd + shift + p, particle: configure, selecting 0.9.0, Argon, putting the current device name and it works.
Also, I had my Argon running a bricking program (Argon bricked or issues with Particle's cloud?) which certainly didn’t help flashing it.
Thank you for your support.