This issue still persists in 24w03a
I've seen invisible chicken jockeys before in previous snapshots, if this still exists in the current snapshot then it should be reported as a separate issue. I can confirm this though, as a few weeks ago I was being chased by "hostile chickens" which were really invisible jockeys.
Well summarised, redstonehelper. Hope this gets fixed soon.
oops
Its acctually all stairs and redstone dust
It is also impossible to give horse and wolf armour to an armour stand with arms. I would expect the armour stand to hold the horse/wolf armour.