Cannot spawn baby skeletons

I can spawn a baby zombie fine using the command /summon Zombie ~ ~ ~

{IsBaby:1}

. However if I swap Zombie for Skeleton: /summon Skeleton ~ ~ ~

{IsBaby:1}

, an adult skeleton is created. If I understand it correctly the mechanics for baby mobs are identical between zombies and skeletons, so this should work?

I have uninstalled all mods and the problem persists.