ARC Keeps Blocking Windows Shutdown

I'm having an occasional issue with Windows shutting down when using the Utility.shutdownPC(); command from an ARC script.

Background and setup:

• I have a looping JavaScript script in ARC that watches a button on my robot. The button is read by an EZ-B v4 ADC port and triggers the script when the voltage changes.
• The PC running ARC (Windows 11) is mounted on the robot and connected to three EZ-B v4 controllers via USB-to-Serial converter cables (EZ-Bs are connected to the PC via USB).
• The script sends ControlCommand calls to various Robot Skills (Soundboard v4, Bender, Head Section, Left Arm, Right Arm, etc.) and then calls Utility.shutdownPC(); to shut down the onboard Windows 11 PC.

Problem: This process has worked reliably for a long time, but within the past week or so I’ve started seeing intermittent failures. When the shutdown hangs, Windows shows a message saying something like "ARC is still running and keeping the PC from shutting down" and offers a button to end ARC. If I choose that option, ARC appears to terminate and Windows then completes the shutdown.

Notes on troubleshooting I’ve tried or considered:

• I do not allow Windows Update to update my Windows 11 OS, so I don’t think a Windows update is the cause.
• I checked ARC’s settings and enabled "Do not display exit confirmation when exiting," but the same occasional hang still happens. I seem to recall that in the past I had that setting disabled and Utility.shutdownPC(); still shut down Windows without my intervention.
• I’ve read suggestions online (e.g., adding switches like /s /f /t 0 to the shutdown command and disabling Fast Startup). Fast Startup is currently enabled on my PC. I haven’t tried these Windows-level changes yet.

Here is the shutdown script I’m using (triggered by the EZ-B ADC port):

ControlCommand("Personality Generator", "PauseOn");
sleep(250);
ControlCommand("Head Section", "ScriptStart", "Bubble Full Up");
ControlCommand("Head Section", "ScriptStart", "Radar 1/4 Sweep");

var Goodbye = Utility.getRandomUnique(1, 12);
print("Goodbuy: " + Goodbye)

if (Goodbye == 1) {
ControlCommand("Soundboard v4", "Track_9");//say "Hasta La Vista"
sleep(2500);
}
else if (Goodbye == 2) {
ControlCommand("Soundboard v4", "Track_10");//say "Love Long & Prosper"
sleep(2750);
}
else if (Goodbye == 3) {
ControlCommand("Soundboard v4", "Track_36");//say "So it Goes"
sleep(2500);
}
else if (Goodbye == 4) {
ControlCommand("Soundboard v4", "Track_83");//say "Pleasure to Serve"
sleep(3500);
}
else if (Goodbye == 5) {
ControlCommand("Soundboard v4", "Track_84");//say "Goodby"
sleep(1750);
}
else if (Goodbye == 6) {
ControlCommand("Soundboard v4", "Track_91");//say "May the Force be with you"
sleep(2750);
}
else if (Goodbye == 7) {
ControlCommand("Soundboard 2", "Track_19");//say "My Power Pack needs charging"
sleep(4500);
}
else if (Goodbye == 8) {
ControlCommand("Bender", "Track_28");//Say "Shows Over"
sleep(3000);
}
else if (Goodbye == 9) {
ControlCommand("Bender", "Track_36");//Say "Wanna Kill All Humans?"
sleep(3500);
}
else if (Goodbye == 10) {
ControlCommand("Bender", "Track_30");//Say "So Long Coffin Stuffers"
sleep(3500);
}
else if (Goodbye == 11) {
ControlCommand("Bender", "Track_3");//Say "Bite My Shiny Ass"
sleep(3500);
}

ControlCommand("Head Section", "ScriptStart", "Bubble Full Down");
ControlCommand("Left Arm", "ScriptStart", "Left Claw Closed");
ControlCommand("Right Arm", "ScriptStart", "Right Claw Closed");
sleep( 1000 );

Utility.shutdownPC();

I’m totally open to suggestions or an updated script to resolve this intermittent shutdown issue where it appears ARC is preventing Windows from shutting down. Thanks!