command line - Why Task Scheduler fails to open a GUI application window when /sc onstart parameter specified?

This works:

schtasks /create /tn calc /tr c:\Windows\system32\calc.exe /sc minute

After running this and a computer restart:

schtasks /create /tn calc /tr c:\Windows\system32\calc.exe /sc onstart

the calc.exe process is present in Task Manager, but the calc window is missing.

When I run the onstart task manually, the calc window shows up:

schtasks /run /tn calc

What I've tested so far:

• calc.exe, osk.exe, cmd.exe


• ping -n 30 127.0.0.1 //a 'sort of' sleep function


• a .bat file which created a new file and writes a line of text inside the file - worked as expected, but there was no GUI window visible


• c:\Windows\SchedLgU.txt log file - no errors

All tasks were run by the user that was in the Administrators group.

Why Task scheduler fails to open a GUI application window when /sc onstart parameter specified (or what am I doing wrong)?