Manual Updating of Cells Linked to External Documents Not Working

I have a reference Calc document linked to several external Calc documents. The reference document is set to automatically link to the source documents. An example of the problem: A cell in my reference document is linked to cell ‘I20’ in one of the source documents, and is displaying a value of ‘245’. But cell I20 in the source document is empty, and the value 245 is in cell I21. (I likely inserted a row in the source document at some time in the past.) When I open my reference document, Calc displays the message “Automatic update of external links has been disabled”. I click “Allow updating”, and expect the linked cells to display the values in the referenced cells in the source document. They do not! I then select menu item ‘Edit’ - ‘Links to External Files…’, and click ‘Update’ in the Edit Links box. Still nothing gets updated.
How can I get my reference document to read the linked values from the source documents?

Please upload two sample files here, with the link. (Use relative references)

Your LibreOffice version?

My links are absolute. If I edit a link (i.e. make it relative), that triggers a manual update for that cell. (So I can’t provide the sample files you requested.) I am using version “ (x64) / LibreOffice Community”.