Delivery Note naming bug

[WebStuff]

Joomla! 3.10.12
VirtueMart 4.2.6
PHP 8.1.9
Isis and VMAdmin Template

I have a weird issue with delivery notes in the backend Orders/Order page.
If I click on the link created with print_links.php I get a delivery note in the browser but the filename saved in the Safe Path is using the COM_VIRTUEMART_FILEPREFIX_INVOICE value instead of the COM_VIRTUEMART_FILEPREFIX_DELIVERYNOTE value.
Checked my overrides and it's using the one from there so don't think its a problem with the actual overrides as the "invoice" one is the one from the file.

Can't seem to find where it's getting it wrong as the layout of the actual pdf created is the correct one, i.e. 'deliverynote'. I only became aware of it after the upgrade to 4.2.6.
Not a show stopper I've worked around it for the moment but thought I'd advise of it.