Either use a different element, or make sure that the heading contains some text.
The engine scans all
h6 headings and elements with role=heading, and checks whether they contain text.
It is misleading to assistive technology users.
<h1>Heading Level 1</h1> <h2>Heading Level 2</h2> ... <h5>Heading Level 5</h5> <h6>Heading Level 6</h6>