SharePoint lists and document quick part issues.

Within our SharePoint site, we've organized a collection of documents alongside several lists, each linked to lookup columns within the Documents folder. These lookup columns, in turn, correspond to quick parts embedded within the documents' footers, generating a unique document code derived from about three dropdown selections.

However, an inexplicable issue arises intermittently, primarily during the initial stages of document creation: these quick parts within the documents often malfunction, failing to display their correct values. What was once a clear selection like "ABC" from the dropdown might inexplicably revert to showing its respective row number from the SharePoint list such as "1". 

The below examples shows a correct list with one that is no longer working correctly.

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Strangely, while users may create multiple documents without encountering any problems, the next document they generate suddenly exhibits this bug, despite following the exact same procedures.

The only known resolution is to delete the affected document. However, even when creating a new document, using the same name as the previous one triggers the same issue immediately. To avoid this, it's necessary to ensure each new document has a unique name.

This persistent issue has gone on for almost two years, causing significant inconvenience. It doesn't discriminate between files generated from a SharePoint template or those directly dropped in from desktop.

None of the files are old versions of word, the problem can arise randomly with a document at any time. Notably, none of the users have OneDrive synced to this site; all operations are conducted directly within the SharePoint site, which operates with major, minor, and draft versions.

Furthermore, it's worth noting that the bug tends to manifest primarily during the initial stages of document creation. Once the document is initially set up with the correct values, subsequent issues are relatively rare.

When quick parts fail, the documents row in SharePoint still shows the correct values for each of the columns for the drop downs, i.e ABC DEF HIJ. However, despite this, the document footer still displays numbers 1-2-3 instead of the correct letter values.

I have spent some time trying to figure out an explanation. Can this still only be summed up as some sporadic SharePoint bug?