Adding a new sub-objective under alignment view is interrupted with the following error message:
You have created Parent-Child relationship and now you are trying to create a new sub-objective, but from the wrong session.
You are in the Parent Session and you want to create a sub-objective, but the respective objective belongs to the Child session.
Please note that by creating a new objective, it will be automatically assigned to the current running session.
By creating of sub-objective, it will be automatically associated/assigned with/to the session of their respectively objective.
You are not able to create a sub-objective from a session, which is different from the objective session.
The error message appears because the new created sub-objective is associated with the session of the objective (Child session), which is different from the session where are you currently working (Parent session).
Please switch to the Child session and try to create the sub-objective. It will work, because the Objective is in the child session and you are currently working in the same session as well.
The below video shows how to reproduce the error and how to solve it.