Updating a custom table on user profile create/save - database

Question

I'm trying to update a row in a custom table (or update if the 'user_id' exists) when creating or updating a user profile. The source data is the 'location' field - an ACF field.
Currently the custom table doesn't get updated on profile create or save. Here's what I have so far:
function copy_location_to_user_locations( $user_id ) {
if ( !current_user_can( 'edit_user', $user_id ) ) {
return false;
}
$location = get_field('location', 'user_'.$user_id); // Needs to match the ACF field name
$latitude = $location['lat'];
$longitude = $location['lng'];
global $wpdb;
$table_name = $wpdb->prefix . 'user_locations';
$data = array(
'user_id' => $user_id,
'latitude' => $latitude,
'longitude' => $longitude
);
$wpdb->replace( $table_name, $data );
}
add_action( 'profile_update', 'copy_location_to_user_locations', 10, 1 );
add_action( 'user_register', 'copy_location_to_user_locations', 10, 1 );
What have I missed?
For reference, my function for creating the custom table is:
function create_user_locations_table() {
global $wpdb;
$table_name = $wpdb->prefix . 'user_locations';
$charset_collate = $wpdb->get_charset_collate();
$sql = "CREATE TABLE $table_name (
id bigint(20) NOT NULL AUTO_INCREMENT,
user_id bigint(20) UNSIGNED NOT NULL,
latitude float(10,6) NOT NULL,
longitude float(10,6) NOT NULL,
PRIMARY KEY (id),
FOREIGN KEY (user_id) REFERENCES {$wpdb->users}(ID)
) $charset_collate;";
require_once( ABSPATH . 'wp-admin/includes/upgrade.php' );
dbDelta( $sql );
}
register_activation_hook( __FILE__, 'create_user_locations_table' );