Home-manager disappares on reboot

as in the title when i reboot my system home manager is not present and i have to manually install it. Why is this happening?
i used the flake installation as a standalone program

Are you really sure you are only using standalone and not mixing it with a system setup?

Does HM also disappear when you nixos-rebuild switch ?

What is the output of systemctl status home-manager-$USER?

Unit home-manager-rocco.service could not be found.
is the output

and no home manager does not disappear in rebuilding system

Then I have no immediate idea, do you mind sharing system and home configuration?

i’ve just managed to solve adding home manager to the system packages in configuration.nix but in my nther pcs i i didn’t have to… Will dig this tomorrow cause today is late night