Mgnifying glass icon not showing

This is because the bridge theme that you are using on your site does not display magnifier icon image.

You can display it by adding the below CSS code in the Custom CSS option of Add Search To Menu plugin settings on the path Settings -> Add Search To Menu

li.astm-search-menu #searchsubmit {
    background: url('https://www.rrtrainers.com/wp-content/uploads/magnifying-glass-white.png') no-repeat #000 center;
    background-size: 81%;
    font-size: 0;
    padding: 9px 12px;
    float: right;
    margin-top: 3px;
}

Please change the image URL https://www.rrtrainers.com/wp-content/uploads/magnifying-glass-white.png in the above code to whatever you want to set.

Looks like magnifier icon doesn’t show on TwentySeventeen theme (current wordpress’ default theme) as well. Can you fix it please? (Example: bumafan.ru)

@mayuxi Issue is reported resolved here https://www.ads-software.com/support/topic/magnifier-icon-not-showing-on-twentyseventeen-default-theme/#post-10048189