Works fine if I use it on my account, but my son's account cannot use the game in kids mode.
The child's account is tied to both mine and his Mother's, so this might be the cause of the issue. Unfortunately it is shared and will not allow her to purchase it now that I own it, so short of getting a refund, completely removing the app and reinstalling it under her side I don't know how to fix this, or if that would even fix it.

It doesn't seem to work with amazon family. I even tried installing the google version, but it seems only the apps downloaded from amazon app store can be shared with a child account.