To enable numeric sorting, you’ll need to convert your identifiers to integers. Here’s how you do this. Perform an advanced search for all items that have an identifier. Then, under “Batch actions,” select “Edit all” and click “Go.” Then, under “Convert to numeric,” select the identifier property and “Convert to integer,” then click “Save.” Once this is done you should see an additional sorting selection, something like “Identifier (numeric:integer)”. Select this to sort integers in numeric order.
It would be great to add a link to the manual in the GitHub repository of the module, for those who - like me - are goign straight to the GitHub repository before opening their eyes…