I've been unable to link a supplier invoice in the new Spend Money In-Box, to an existing Spend Money payment - even though the payment included the name from the Supplier Card.
However, I got around this by using Attachments in the Spend Money window.
Kym Yeoward
Darwin (Palmerston)
"New Spend Money In-Box - not working for existing transactions"
Sorry for a late reply, I didn't spot your post until now. For some reason, it looks like the Link to Existing Spend Money works for some customers and not others depending on which Azure Cluster you happen to be on. This is something that will be completely fixed in the 2019.4 deployment.
Though we did release code into the 2019.3 branch to patch this, I believe there's talk to deploy this so that it fixes this issue prior to 2019.4. I'd suggest keeping an eye on that post to hear more if that becomes a reality.
This has now been fixed with the release of AccountRight 2019.4. You are now able to link Documents to all Spend Money's created in current and prior versions.