No changes to CSV file using Scheduled Task

Hi, I have a very simple script that changes a CSV file. When I run this via a Powershell console it works fine but if I try to run it in a Scheduled Task no changes are made, though the task said it ran successfully. I've tried running the task with highest privileges, a different account and running whether the user is logged on or not but nothing helps.

Code (c:\scripts\test.ps1):

$csv_info = Import-Csv c:\scripts\test.csv

foreach ($line in $csv_info) {

	$log_drink = $line.Drink

	if ($log_drink -eq "Water")
	{
		$line.drink = $line.drink.replace("Water","Coke")
	}

}

$csv_info | Export-Csv test.csv -Delimiter ',' -NoType

The CSV file looks like so:

"Name","Drink"
"John","Water"

I also granted full permissions to 'Users' to the directory and files but it makes no difference. Does anyone have any tips?