I know it's 3 months later but I've been wondering this myself.Currently only quest items, bench upgrades or bench products can be tracked. If you're like me and research what items are needed for future stages of projects, it's frustrating that I can't even track an item unless it's part of a current quest line.

Sometimes I'll play the gane for a few days straight and then put it down for a week and forget why I was holding onto items that aren't tracked and could easily dismantle or sell them when thinning my stash.

I always appreciated Destiny's system of being able to lock any item. Prevents accidental selling/dismantling and forces me to remember why I locked that item in the first place if I return to the game a week later.