I see logo thumbnails in the backend but not on frontend?

…If you use WP Job Manager

Due to a WP Job Manager limitation (not Go Fetch Jobs) Logos will only show up on the frontend if the company name is filled . If you want to show logos even when the company name is empty here’s a piece of code that you can paste on your theme ‘functions.php’ to ignore empty company names. You can replace ‘N/A’ (not applicable) with anything you want as long as it’s not an empty value,

add_filter( 'the_company_name', 'my_gofj_ignore_empty_company', 10, 2 )
function my_gofj_ignore_empty_company( $company_name, $post ) {
    if ( ! $company_name ) {
       return 'N/A';
    }
   return $company_name;
}

… Other Reasons

Since some of the logos pulled from RSS feeds are from images stored on CDN’s they cannot be stored as native WordPress featured images in the media library. This means that if your theme does not use the default theme/plugin custom function to display jobs on the frontend these logos may not be displayed. You’ll need some custom changes to be able to do display logos in that case.