8.5 RU3 and 1903 - agent not being installed during Windows install

I have a fairly rudimentary job that had been working flawlessly to perform a scripted install of Windows 10 1903:

• Erase Disk
• Partition Disk
• Install Windows
• Boot to Production
• Join Domain

Since upgrading to 8.5 RU3, my Windows install jobs are now getting stuck at "Boot to Production", which times out after an hour. The PC has a working install of Windows 10 1903, but the agent was not installed, so it's never able to communicate back to the NS that it successfully booted into production.

Thought?

Thanks!