Position "fixed" moves when scrolling down the page on the mobile

Create a div with position:fixed;top:0. In computing it is normal, and does not move independently if I go down or up the screen, but on the mobile when I go down the screen it comes out, but if I go up again it appreciates fixed at the top again. Does anyone know how to solve this? below as this the div:

<div class="menu">
  MENU
</div>

.menu{
 position:fixed;
 z-index:9;
 top:0;
 width:100%;
}

css posicionamento

Author: Leandro Marzullo, 2019-04-12

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