I was having the same issue and found this topic. I found a relatively simple solution to this. This works in the 2023 Pro version. I'm not sure if it'll work in previous versions.
From plan view, click on the object that contains the missing items.
From the bottom toolbar, select the "Find Original in Library" button. It's the last icon on mine.
Select the missing item/items you want to extract from the pop-up window.
When you click the "OK" button, it will display the selected object name and its associated library.
Select the missing items and click the "Add to Library" button to save these items to the User Catalog.
Hope this helps others!
