Whenever I use the command " /summon EntityHorse ~-1 ~ ~2 {Tame:1,Saddle:1,Leashed:1,Leash:{X:-530.3,Y:56.0,Z:747.4}} " the horse will spawn with a lead attached to a fence post, however the lead will not render. The only way to get the lead to render is to log out and log back into the world.

Steps to reproduce (command block)

1. Run this command:

   /summon Pig ~ ~ ~ {UUIDLeast:1l,UUIDMost:1l,Health:0.1}

2. Run this command:

   /summon Pig ~ ~ ~ {Health:0.1,Leashed:1,Leash:{UUIDLeast:1l,UUIDMost:1l}}

3. Reopen the world

Steps to reproduce (structure block)

1. Save a structure with a mob on a lead, attached to a fence
2. Remove the mob
3. Load that structure in the same place (MC-102170)
4. Reopen the world

Code analysis: https://bugs.mojang.com/browse/MC-55851?focusedCommentId=284856&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-284856