– Use a child-theme https://ronangelo.com/frontier/
– Copy loop-blog.php from the parent-theme to your child-theme folder
– Open your child-theme loop-blog.php and find this line:
<?php if ( frontier_option('blog_display', 'excerpt') == 'excerpt' ) : ?>
Replace it with this line then save:
<?php if ( frontier_option('blog_display', 'excerpt') == 'excerpt' && !is_sticky() ) : ?>