Why for some resource sometimes is not appears 'Add assigned task' and how can we added.
The "Add assigned task" was not visible in the New user experience because ETC was not specified for the task.
In order to see the ‘Add assigned task, the task start and finish date has to cover the range specified and also ensure ETC is always set.
Furthermore, the tick which is automatically enabled in the ‘’Add assigned task’’ cannot be removed by default.
The new user interface is an out of the box option and not an object. Due to limited configuration via the UI this tick is enabled automatically.