I'm not sure it didn't apply to your horse because it was dead. I got the message a bunch and there are lots of items I can't craft, even though I know I was wearing them when I got the message. I think it is simply broken in regards to some items.
I got the message a few times on my gimmick gear load out which is leather cap, leather apron, rus cav boots, leather gloves and the shitty 1h meat cleaver. I can craft the leather cap, apron and boots but not the gloves or cleaver.