Hi Paul,
Actually, the template has been updated on www.pizzeria-eindhoven.nl and also www.nemocura.com
Nemocura is behaving ok, hamburger icon visible black on white background,
Pizzeria is not ok, hamburger icon is white on white background, change in preset has no effect.
Besides that, after opening the mobile menu on Pizzeria the background is blurred and the mobile menu misses the white background.
I remember that this error appeared also a few months ago on several websites, after an update of the Helix template.
Kind regards,
Edze de Boer