SVG Icon Not Displaying Black Fills

Any idea on what might be interfering w/ the display of the button icon outlines (below the page title); they should be black are instead white: https://musicianstoolshed.com/lesson-dashboard/

I tried optimizing the SVG and also tried canceling all custom css but didn't get on positive results.

Any suggestions of what I could try?

Is there a limit to SVG icon feature of GP?

Thank you!