That should have worked. Background commands are elevated commands by default because they run in the context of the Windows service that runs as Local System.
I have a background command called "Restart Print Spooler" that runs:sc stop spooler & sc start spooler
I just tested it on my Win10 box and it worked. I have UAC turned on though, so maybe that's the difference.
Check out this solution too: https://www.triggercmd.com/forum/topic/1453/questions/2