Compatibility issue breaks the backend product search

Hello.
I m not plugin developper, but I finally tried to have a look there…
The issue seems to be located in the function : extend_admin_search() that is called in case the option to admin-search in GTIN is ticked.
The thing is that both plugin are hooking the meta_query element of the query object. But this plugin just set the meta_query array without testing if the element already exists.

So by replacing those lines :

$meta_query = array( 'relation' => 'OR' );
			array_push( $meta_query, array(
				'key'     => '_wpm_gtin_code',
				'value'   => $search_term,
				'compare' => 'LIKE'
			) );

by those ones :

$meta_query = $new_query->get('meta_query');
			if( empty( $meta_query ) ){
				$meta_query = array();
			}
			array_push( $meta_query, array(
				'relation' => 'OR', 
				'key'     => 'wpm_gtin_code',
				'value'   => $search_term,
				'compare' => 'LIKE'
			) );

seems to fix the issue.

Dear Emanuela could you please confirm this is the correct way to fix that issue ?

I had the same problem with WooMultistore and above solution from @sb5 worked for me.

I hope it will be fixed in a newer update of this plugin.