reported in game as well but I figured I'd post it here so people will know.
If you make a multi prim item where one or more prims are set to phantom (via script) and others prims are not phantom, then link them together they work fine as intended.
If you take the same item and move it into inventory, then out it fails. If the phantom item was a child it will no longer be phantom. If the phantom object was the parent the entire item will be phantom.