When the action figure bundle is equipped, the LeftFootAttachment and the RightFootAttachment are not properly generated in left and right feet respectively.
Above is two of the same characters, one with the action figure bundle and one without it. You can see the attachment is not in the feet as they do not overlap like in the character without the bundle
Above is the hierarchy of the feet of the action figure bundle.
Bumping this because my team just encountered this and we were stumped as to why only one of our team members were experiencing a bug for nil references to the RightFootAttachment/LeftFootAttachment on their character. They were using the Roblox 2.0 Package and were the only one experiencing the error since we look for these attachments on spawn to attach things to them.