I spawned in a horse along with a saddle and armor for it. Taming and equipping the saddle worked fine for it, however, when attempting to equip the diamond armor the horse proceeded to turn invisible. I was still able to interact with the horse and ride it but clicking it was guesswork. I also tried it with golden armor and it yielded the same results.
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However, this issue is a Duplicate of MC-137563.
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