These are windows 7 SP1 vms, I created the parent image from scratch, and as I say it was working but something changed somewhere and I can't figure out what. I'm going to try and create a new one but I'm not sure that is the problem.
You may be right, the release notes say
- Enabling remote profile loading took longer than the default value of 15 seconds and failed to initialize Client Drive Redirection (CDR). This issue has been fixed. When you launch a VDI session and log in, the Share Folders option on the client toolbar and network drive for CDR are available. All redirected drives are accessible.
- If the Persona Management log file is rotated before the user logs off then the file is not uploaded to the network share even though the "Upload log to network share" group policy is enabled.
- Horizon Agent and Horizon Connection Server have updated 7-Zip to version 16.04 to resolve security issue CVE-2016-7804.
- When there are two NICs installed on the VM on which Connection Server is installed, Horizon 7 version 7.2 events are not written to the Microsoft SQL database.
- The mouse pointer stays as sand watch for an application session that uses the PCoIP protocol.
- You cannot use nested Active Directory OUs that contain the same name in Horizon 7.
- The access groups creation limit has increased from 100 to 200.
- A desktop pool configured with Horizon Persona Management does not apply the wallpaper specified in a GPO setting to desktops.
- The upgrade process fails when you upgrade a replica server from 7.2 to 7.3 when CEIP is disabled.
- Automated pool provisioning fails to provision new VMs after an upgrade to 7.3, if vCenter Server uses a CA-signed certificate.
- Automated pool provisioning can halt while using VSAN 6.6.1. Use ESXi 6.5 Express Patch 4 to resolve this issue.
I'm wondering if its the nested OU part I was placing my vms in EUC\Desktops\Production\<pool name>. I'll have to upgrade and see if that fixes it.