Just to emphasize what Barry has said. The Pack Project function only makes a copy of the items that are used in the timeline.
Any unused media in the library will be omitted from the pack location. There are certain other things that are not included in the 'Pack location', but I am not sure what they are. Maybe someone who knows will chime in so that you will be aware of what you will not have after packing.
What I have a habit of doing, before I pack a project. I insert a spare track(s) and copy all unused media from the library to the new track. Then pack the project.
Hal
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