There's a bug. Whenever I craft and my inventory was full, I couldn't get that item I crafted to my inventory. In my instance, it's the "raft" item.
To mimic this error/bug, do the following:
1. Fill up your inventory to the point that there are no slots available.
2. Craft any item (preferably a raft or any item that's not in your inventory). Obviously, that item will drop instead.
3. Empty a slot by putting some stuffs into a chest or by throwing it.
4. Craft the same item again (In this instance, the raft).
5. You can see that even if there are free slots, the raft can no longer be made.
NOTE: Make sure that you don't have any raft in your inventory.