Paul,
I opened the code inspector on my PC. I am not using SPPB 4.x and am using the Helix Ultimate as my template.
I do not have any color selected for the hamburger icon.
<div class="burger-icon" aria-hidden="true"><span></span><span></span><span></span></div>
However, I did have a banner scrolling across the top of my page in the top-content position. I had to eliminate this to get the off canvas mobil menu working again last night.
So I either don't use the scrolling banner or we need better documentation to adjust whatever the size issue is causing the problem.
Thank you,
Donna