MSIX appinstaller UpdateSettings

I have an MSIX and associated appinstaller file.  Within the AppInstaller I have various Update settings such as OnLaunch / HoursBetweenUpdateCheck =0, ShowPrompt=true and automaticBackgroundTask.  When I install the app using the appinstaller, this works, and the app launches.  If I then close the app, and try to launch it again, the appinstaller prompt is launched, but with the message "Cannot Open App Package : failed due to unknown reason".  In logs, I have the message "Error code: Activation is blocked due to the .appinstaller update settings for this app.. Activation phase: Deployment".  Anyone come across anything like this?  I have tried changing the AppInstaller Uri and the MainPackage Uri to local files (C:), mapped network drives and UNC paths.  But the same appinstaller works for the initial installation, then fails on the update check.