My first thought was there was some type of lockout but I couldn't find anything to press and it felt like there was something actually blocking the shifter from going in to gear. I started feeling things through the bag and could tell there was definitely something there. I played around with removing the bag and finally just ripped it off (which is actually what you're supposed to do, so that worked well) and this is what I found.
Image 1
This picture is to illustrate how it blocked the shifter when I tried to put it in reverse:
Image 2
The third image is of the actual bolt and 'head' I took out. I have since reinstalled the bolt, minus the head.
Image 3 
