Some Material Icons not working with Angular Material

I am trying to use the keep Material icon but it's not working.

When I use the following HTML, I am able to see the first two icons, but not the keep one. I've noticed this issue with other icons too. Any idea what the issue could be?

<mat-icon
aria-hidden="false"
aria-label="Example home icon"
fontIcon="home"
></mat-icon>
<mat-icon
aria-hidden="false"
aria-label="Example home icon"
fontIcon="grading"
></mat-icon>
<mat-icon
aria-hidden="false"
aria-label="Example home icon"
fontIcon="keep"
></mat-icon>




Link to StackBlitz showing the problem

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