Problem With custom Filter

HI,
Thank you so much for the awesome plugin. I am trying to create a custom filter for city field.
I have create a custom field called city with meta _city.
I have used code from a previous thread
https://ww.wp.xz.cn/support/topic/location-dropdown-event-filter/
But the filtering is not working. Can you please let me know what else I have to make it work.

Here is the code

add_action( 'event_manager_event_filters_search_events_end', 'filter_by_city_field' );
function filter_by_city_field() {
	?>
	<div class="search_event_types">
		<label for="search_event_types"><?php _e( 'City', 'event_manager' ) ?></label>
		<select name="filter_by_city" class="event-manager-filter">
			<option value=""><?php _e( 'Choose your city', 'event_manager' ); ?></option>
			<option value="mumbai"><?php _e( 'Mumbai', 'event_manager' ); ?></option>
			<option value="pune"><?php _e( 'Pune', 'event_manager' ); ?></option>
			<option value="delhi"><?php _e( 'Delhi', 'event_manager' ); ?></option>
		</select>
	</div>
	<?php
}

/**
 * This code gets your posted field and modifies the event search query
 */
add_filter( 'event_manager_get_listings', 'filter_by_city_field_query_args', 10, 2 );
function filter_by_city_field_query_args( $query_args, $args ) {
	if ( isset( $_POST['form_data'] ) ) {
		parse_str( $_POST['form_data'], $form_data );
		// If this is set, we are filtering by city
		if ( ! empty( $form_data['filter_by_city'] ) ) {
			$event_city = sanitize_text_field( $form_data['filter_by_city'] );
			$query_args['meta_query'][] = array(
						'key'     => '_city',
						'value'   => $city,
						);
		}
	}
	return $query_args;
}

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