H1 GIF animation

I got this code for animating my header. But, for some reason it works with H2-3, but not my H1. The code is below. I think there is something going on with the custom css on my site. Can someone take a look?

// GIF Text //

h1 {
  background: url(GIF-URL-HERE.gif);
  background-size: cover;
  background-position: center;
  -webkit-background-clip: text;
  color: transparent;
  }

difficult to help without url