FileMaker Perform Applescript step

I have posted this question in a FileMaker forum but I think I need some help from someone here.

It appears that Applescripts used in a Perform Applescript step do not get to send a timeout specification. Here is a script that when I compile and run it as a script, takes about 8 minutes to complete. So there is no error since I have included the “with timeout of 600 seconds”.

set source_path to "Folder:Of:Many:Large:Files:"
set dest_path to "Destination:Folder:"

tell application "Finder"
		with timeout of 600 seconds
			set new_path to (duplicate item source_path to folder dest_path with replacing) as string
		end timeout
		set success_status to 1
	on error errMess number errNum
		set success_status to 3
	end try
end tell

tell application "FileMaker Pro"
	tell document "AppleScripts"
		if success_status is 1 then
			set cellValue of cell "g_script_result" to new_path
			set cellValue of cell "g_script_result" to errMess
		end if
		set cellValue of cell "g_AS_Done" to success_status
	end tell
end tell

That same applescript run from inside a FileMaker script will timeout after 2 minutes. It seems like FileMaker is the sender of the Apple event and so it sets the timeout specification, but the Applescript receives the timeout error. I am so confused.