@tony-brunsman I figured it out! I removed the second if statement, and it works now. Thank you so much for your help, much appreciated!
export function radiobuttongroup1_change(event) {
//Add your code for this event here:
if ($w(‘#radiobuttongroup1’).selectedIndex === 2) {
$w('#box').expand();
} **else** {
$w('#box').collapse();
}
}