New Post: InstallationUI_Timeout not timing out

Show-InstallationWelcome -CloseApps "excel,groove,onenote,infopath,outlook,mspub,powerpnt,winword,winproj,visio" -ForceCloseAppsCountdown 300 -PersistPrompt -AllowDeferCloseApps -DeferTimes 1 -CheckDiskSpace

1) Try using -AllowDeferCloseApps and see if it work?
2) I see your -ForceCloseAppsCountdown and InstallationUI_Timeout are both set as the same value. Do you want the welcome screen to timeout and quit the script or force the close the apps if no response after 5 mins?

For testing maybe you can reduce the -ForceCloseAppsCountdown and the <InstallationUI_Timeout>300</InstallationUI_Timeout> to know if the script is working as expected.