YUP what Godofgods and Mt. zion said. I rescued a breeding herd our aunt left us when she passed away. Many of my forsters and the ones I kept were missing ears, toes, missing feet, and one had no tail at all. I first thought all of it was from fights but then I learned about the mother over grooming babies and If they had a hard birth the mom will pull on the foot or tail to get the breech baby out. If the kit was just born I would have rubbed it hard with a blanket to try and get it to come back. We did that with pups when I worked at the vets and it works many times. A hard birth can kill the baby or the mother and baby. You are lucky only one baby died and not mom and baby. 2 out of 3 is good for a chin.
Sounds like you and your chin are still learning the ways. Congrats on your first batch. I thought about breeding but I am going to stick to rescue.
Here are my babies. seemed like the mosaic had the bad ears out of my rescue herd. These males came to me with these ears. It gives them more character not like they need any more they are the BEST! .
20171018_220338 by
Sarah Ireland, on Flickr