Line 381 functions.php
if ( is_page_template( 'page-templates/full-width.php' ) || is_attachment() || ! is_active_sidebar( 'themonic-sidebar' ) ) {
make it like this
if ( is_page_template( 'page-templates/full-width.php' ) || is_page_template( 'page-templates/buddypress.php' ) || is_attachment() || ! is_active_sidebar( 'themonic-sidebar' ) ) {
This is when buddypress.php is in a page-templates folder. If it doesn’t work, try without child theme.