When leaving a cart horse or boat there is a 5% chance it turns invisible alongside all additions such as the saddle or horse armour (all types). I can still stand on the boat or collide with the horse/cart but it cannot be hit or ridden. Exiting the world and re-entering causes the entity to reappear and all problems are fixed. This is not much of a problem once I worked out this but the frequency of occurrence is annoying. This bug has not occurred for untamed horses or pigs but does occur when kicked of a horse due to water. The bug also does not occur when riding and leaving horse, boat or cart.