My named horse with diamond armor and a saddle seems to have despawned. He was attached to a fence post with a lead. The lead graphic is still attached to the post, but it wasn't attached to anything else. The horse could not have escaped the location surrounding the fence post. I've had this horse since I started the game and I'm really heartbroken.
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We're already tracking this issue at MCPE-21416, so I will resolve and link this ticket as a duplicate.
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Can confirm a named horse despawned in our game too. The main host is on xbox one and we're on 13.1 The horse was secure in a stable and poof! Just gone.