It appears that when installing from the original bat file via SCCM deployment, citrix receiver exe installer extracts files to C:\Program Files (x86)\Citrix\ICA Client
And then runs the installation from there. This is where selfserviceplugin.exe runs from and installs fine.
When deployed using the Powershell App Deploy Kit, the same exe extracts its files to C:\Windows\SysWOW64\config\systemprofile\AppData\Local\Citrix\SelfService\Program Files
And I believe this is causing the issue – whatever the issue is.