"child" and "latest" of container does not work properly

If the container has an attribute “mni”, let’s say 1,
Then we continue creating contentInstance under that container,
After creating like 100 contentInstance, the container will be dead.
When I say “Dead”, I mean when I try to get “http://localhost:8282/InCSE1/TestContainer/latest”
I will receive

{"error":"Resource target URI not found: /InCSE1/TestContainer/latest"}

And I notice that the creating contentInstance still shows "success" and the parent container does updated (the "st" and "lt" updated), but the "ch" stop updating.

You can try it yourself with the following collection.

https://www.getpostman.com/collections/943a20019fec1abb7231

How to test:
Create a container, create contentInstance, see the “latest” does work
Continue creating the contentInstance use the same command for like 100 times.[Continue Click post]
Use the same link earlier to get the latest

My python script that can create ContentInstance each second.
https://github.com/wucangji/Iotdm-python-library

Not sure whether this was caused by setting the "mni".