seems to me unattended install (WDS properties - client) is not working in Server 2019.
After booting my clients from WDS the settings of the under "architecture" stored answer file (the same I used with Server 2016) are not applied. On the clients the folder X: \ Sources \ wdsunattend remains empty. Normally the above configured file should be there as wdsunattend.xml.
Actually I'm running two 2019 servers with WDS installed, both with the same effect.