Mitch SynthSheath issues

[Rayna]

Even with a synthsheath in my inventory, I am unable to give one to mitch. Am i doing something wrong?

 

[TheShepard256]

Some NPCs that can be given SynthSheaths require that you've unlocked or read the item's Codex entry; using it on yourself or an NPC without that requirement (e.g. Penny) will unlock the entry.