When changing to standing from sleeping, mannequins fall one block

Do the following, in a way that the mannequin is summoned well above the ground:

/summon mannequin ^ ^ ^3 {NoGravity:True}
/data modify entity @n[type=minecraft:mannequin] pose set value sleeping
/data modify entity @n[type=minecraft:mannequin] pose set value standing

You will notice that the mannequin is left standing one block lower than it was summoned.