Casting invis on an item doesn't make it invisible.

[Ranfir]

c invis arrow
A Dryad Hunting Arrow fades out of sight.

[3405/3405 797/978 688/688 273|   ] (SU) < > 
( )
id arrow
You identify a Dryad Hunting Arrow:

Object 'dryad hunting arrow' is type weapon.
Extra flags: none.
Weight is 0, value is 130, wear level is 1.
Wear location is wield.
Weapon type is arrow.
Damage is 6d4 (average 15).
Damage noun is pierce
Adds invis object flag.

[3405/3405 797/978 688/688 273|   ] (SU) < > 
( )
i
You are carrying:
     a Dryad Hunting Arrow

[anhegofcherek]

Well-found! I believe this was unrelated to the port though. I think this is a subtle bug relating to how object-flag affects work (or don't work, as the case may be!)