ssh-keys disappears from the shell user authorized_keys file
Each time you save a change in shell-user, the first of the ssh-keys disappears.
If you have 5 keys in /root/.ssh/authorized_keys they get saved along with the generated client public key in the created shell-user authorized_keys file. So there is a total of 6 keys
If you add one custom ssh key to the user, it gets added to the bottom, but then the first of the root keys gets removed. If you remove the custom user ssh key, then it gets removed but the first key from the user authorized_keys gets removed also.
I'll make a pull request with the fix to this bug