monsterinsights_ampforwp_analytics_dimensions_fix.php

<?php

add_filter( 'ampforwp_google_analytics_fields', 'monsterinsights_ampforwp_analytics_dimensions_fix', 11 );

function monsterinsights_ampforwp_analytics_dimensions_fix( $ga_fields ) {
	
	$options = new MonsterInsights_Frontend_Custom_Dimensions();
	$options = $options->output_custom_dimensions( array () );
	
	$ua = monsterinsights_get_ua_to_output( array( 'amp' => true ) );
	if ( empty( $ua ) ) {
		return $ga_fields;
	}
	
	$dimensions_data = [];

	if ( ! empty( $options ) && is_array( $options ) ) {
		foreach ( $options as $optionname => $optionvalue ) {
			if ( monsterinsights_string_starts_with( $optionname, 'dimension' ) ) {
				$num           = str_replace( 'dimension', '',  $optionname );
				$dimensionname = str_replace( 'dimension', 'cd',  $optionname );
				$optionvalue   = str_replace("'set', 'dimension" . absint( $num ) . "', '", '', $optionvalue );
				$optionvalue   = rtrim( $optionvalue,"'" );
				
				$dimensions_data[$dimensionname] = $optionvalue;
				
			}
		}
	}
	
	$ga_fields['extraUrlParams'] = $dimensions_data;
	return $ga_fields;
}