How to properly animate a gun rigged to a character?

The gun is a descendant of the character with its own animation controller inside of it.
The gun is attached to the character with a motor6d in the right hand connected to the handle.

The animation properly animates the character & the gun’s magazine in the animation editor. See Example 1.

Example 1:
https://gyazo.com/0a049b6ee8294fc796566ca8dac4d016

Problem: However when I upload it into the game, only the character animates and the gun’s magazine no longer does anything

https://gyazo.com/ae8aa14cc4aa6247a58f3515ce332e0d

Does anyone know how to replicate the gun animating properly as well as the character?