Some female models don't have a 'relaxed' animation where they drop their hands to their sides. As far as I know all the male models do this. Some of the female models do but not all. This is easy to check and verify, just by making level one characters. Is this is a feature? Unfinished code? A bug? Curious what the deal is with this issue.
Here is a female gnome, who has the at ease position.
https://imgur.com/58LFSE8
Here is a halfling female, who has the at ease position.
https://imgur.com/v3nKKwQ
Dwarf, gnome, halfling, iksar, ogre, troll, all work.
Human, dark elf, high elf, barbarian, erudite, half elf, woof elf, do not work.