Why can't I send an item to recycle?

We remove inventory by using sending to recycle.  This marks it as consumed and item then shows in orange.  Occasionally the item we are trying to recycle won't let us, the button stays grayed out.  We have been deleting these but i'd really like to know why we can't recycle some items?


The "Send to Recycling" function on the Inventory > Receive Inventory page is meant to allow items that originally came from the Recycling module, to be allowed to go back to Recycling. As of November 2016, this feature does not allow items that were received originally in the Inventory module to be sent to Recycling, only items that originated in Recycling.