Unfortunately, it's gone. Bungie can't restore lost items. https://www.bungie.net/7_I-accidentally-dismantled-an-item-I-wanted-to-keep/en/Help/Article/12211 (article title says "accidentally dismantled" but it applies to glitch lost items too) As with any new feature, there are bound to be bugs. Use at your own risk. Some people have had items reappear in their inventory some time after being lost during transfer due to lag. Hopefully that happens to you. If not, good luck getting another one.