In game thumbnails posing weird

In the past I have made conversions of in game items to different life stages, but since the infant update I wanted to try making conversions using some toddler custom content of creators I like named Casteru (Their TOU states that permission isn't needed for conversions stated here: www.patreon.com/casteru/about) I've made my mesh and everything seems to be fine in game and in cas but the character thumbnails have the sims arms looking broken? The infant seems to moving perfectly fine in the game, I just don't know how to make this weird posing go away. I tried deleting the weights and reapplying them with a different reference mesh, but it still doesn't seem to go away. I would appreciate the help, thank you  

Here are some examples: Images

and here is the Blender file: Blender File