Put the summary of the bug you're having here

when i spawned a horse in and put armor on it, no mater if it was iron, gold or diamond armor, the horse just goes invisible, even the saddle disperses when horse armor is applier to the horse. this happened in the first 1.14 snapshot, i tested it out in the latest one and the bug is still there

Steps to Reproduce:
1. tame a horse
2. put a saddle on it (optional)
3. put any type of horse armor on it
and now you have an invisible horse