Load courses only from a cateogry XX in the mobile app.

functions.php

add_action('rest_api_init',function(){
	add_filter('bp_course_wplms_filters',function($args){
		if(empty($args['tax_query'])){
			$args['tax_query']=array(
							'relation' => 'AND',
							array(
								'taxonomy'=>'course-cat',
								'field'=>'id',
								'terms' =>array('xx','xx')
							)
						);
		}else{
			$args['tax_query'][]=array(
								'taxonomy'=>'course-cat',
								'field'=>'id',
								'terms' =>array('xx','xx')
							);
		}

		return $args;
	});
});