Applescript Dialog Box not going away after Big Sur

I have a Folder Action Script that I cobbled together a while back that monitors when a USB drive is attached, then looks for a shell script on that drive and runs it if I tell the Folder Action Script “Yes”. If I click “No” it closes out the dialog and all is well.

It still works at the heart of things, however now when I click “Yes” the dialog box stays visible until the shell script completes, whereas in the past it would disappear immediately after clicking “yes” or “No”.

Any help is greatly appreciated, and thanks in advance!

Code:


property dialog_timeout : 60

on adding folder items to this_folder after receiving added_items
	set shFiles to {}
	repeat with current_item in added_items
		try
			set end of shFiles to ((current_item as text) & ".Autosync.sh") as alias -- check if ".Autosync.sh" exists      
		end try
	end repeat
	if shFiles is not {} then
		tell application "Finder" to set the folder_name to the name of this_folder
		-- find out how many .Autosync.sh  
		set the item_count to count shFiles
		--create the alert string  
		set alert_message to ("External Drive Attached" & return & return) as Unicode text
		if the item_count is greater than 1 then
			set alert_message to alert_message & (the item_count as text) & " new drives have "
		else
			set alert_message to alert_message & "One new drive has "
		end if
		set alert_message to alert_message & "been attached, in folder " & «data utxt201C» & the folder_name & «data utxt201D» & "."
		set the alert_message to (the alert_message & return & return & "Would you like to run Autosync?")
		activate
		display dialog the alert_message buttons {"Yes", "No"} default button 2 with icon 1 giving up after dialog_timeout
		set the user_choice to the button returned of the result
		if user_choice is "Yes" then
			repeat with shFile in shFiles
				try
					do shell script quoted form of POSIX path of shFile
				end try
			end repeat
		end if
	end if
end adding folder items to