Excerpt keep stripping tags

add_filter( 'get_the_content_limit_allowedtags', 'get_the_content_limit_custom_allowedtags' );

function get_the_content_limit_custom_allowedtags() {
// Add custom tags to this string
return '<script>,<style>,<br>,<em>,<i>,<ul>,<ol>,<li>,<a>'; 
}

You can also add this code in your functions file and customize which tags you want to allow in excerpts.