Yeah, fresh install.
I used guide from: https://community.volumio.com/t/beta-raspberry-pi-boot-from-usb-nvme/65699
The plugin is version 3.4 (stable).
As I said before this happens only on this version of volumio ( 3.639 RC-Testing ), on the official release (3.631) the plugin worked flawlessly.
Thank you once more.