Added code to single.php but not recognized

Using child theme. The post is using Classic Editor. I added this code to single.php – basically asking single.php to use includes/trips.php rather than loop-index.php if post is in category saltwater or us-based but it does not recognize trips.php. To test I renamed trips.php to loop-index.php and it ran the file correctly. How do I get it to recognize trips.php? trips.php actually seemed to be working but I switched to advanced layout editor and then back to classic and now it doesn’t work.

<main class='content units <?php avia_layout_class( 'content' ); ?> <?php echo avia_blog_class_string(); ?>' <?php avia_markup_helper(array('context' => 'content','post_type'=>'post'));?>>
<?php
if ( (in_category('saltwater') || in_category('us-based')) && !is_user_logged_in() ) { 
get_template_part( 'includes/trips' );                  
/* Run the loop to output the posts.
* If you want to overload this in a child theme then include a file
* called loop-index.php and that will be used instead.
*
*/                
 } else {
get_template_part( 'includes/loop', 'index' );
...					
?>
<!--end content-->
</main>