ArmorStand's Rotation is wrong in some complex commands

This is command that summoning small block chair.

summon ArmorStand ~1 3 ~ {
CustomName:"chair_root", CustomNameVisible:false, NoGravity:true, Invulnerable:1, DisabledSlots:2039583, Invisible:true, Tags:
["r2","r2chair","r2chairbase"], Team:"deco", Rotation:[90f],
Passengers:[
{id:Slime,NoAI:1,Team:"deco",Size:0,Invulnerable:1,Rotation:[90f],Tags:["r2","r2chair"],CustomName:"chair_middledisplay",ActiveEffects:
[{Id:14, Amplifier:0,Duration:100000, Ambient:false, ShowParticles:false}],
Passengers:[{id:ArmorStand, Invisible:1, CustomName:"chair_display", Rotation:[90f],CustomNameVisible:false, Team:"deco", Pose:
{LeftArm:[-30.0f,270.0f,120.0f],RightArm:[-30.0f,90.0f,240.0f]} ,HandItems:[{id:"minecraft:stick"},{id:"minecraft:stick"}], ArmorItems:
[{},{},{},{id:"minecraft:stained_hardened_clay", Damage:13s, Count:1b}], NoGravity:true, Invulnerable:1, DisabledSlots:2039583, Tags:
["r2","r2chair"], Small:true}]},
{id:"EntityHorse", Team:"deco", Invulnerable:1,ActiveEffects:[{Id:14, Amplifier:0, Duration:100000, Ambient:false, ShowParticles:false}], 
NoAI:1, Rotation:[90f],CustomName:"chair_seat", Tags:["r2","r2chair"]}
]}

Chair's structure : Base ArmorStand - Middle Slime & Horse - Block Display ArmorStand(from Slime)
But the "chair_display" ArmorStand's rotation is wrong(screenshot 1); and its works well when kill middle slime.(screenshot 2, /kill @e[type=Slime,tag=r2chair])