Problem Statement: When you are updating a learning object-level course package for an online course, you must do the following:
Select Edit on the online course.
Navigate to the "Outline" section.
Select "Add Learning Object" (??)
Select "SCORM 2004" as if you were adding a new package.
Select "Replace an Existing Lesson" within the "Select the Update Behaviour" section.
This is very confusing, as you would expect to select the "Edit" icon next to the learning object you intend to update
The UI is telling you to "Add Learning Object" when your intent is to replace an existing course package for an existing learning object. Further, you can only find this option if you go all the way toward adding a new, fresh learning object - only then do you find that this option to replace exists.
Solution: Move or copy the "Replace an Existing Lesson" option to the "Edit" icon next to the learning object you desire to replace/update.