Hamburger menu bug on responsive desktop

The hamburger menu icon disappears or turns white after it is clicked on desktop (both Chrome and Microsoft Edge browsers). This occurs on your demo site as well https://lite.givingpress.com/.

To reproduce:
1. resize window so hamburger menu appears
2. click hamburger menu icon
3. move cursor away

The result is that the menu button is all white with no visible hamburger icon.

4. toggle it closed again

The result is the menu button remains all white with no visible hamburger icon.

Reloading the page sets the icon back to gray, but the bug can be reproduced again.