Hi Mark,

for example, read Helix Ultimate documenation tip >> https://www.joomshaper.com/documentation/helix-framework/customization-tips#offcanvas-menu-how-to-display-all-submenu-items-expand-all

Problem on your site may be also from wrong Menu module settings.

Solution: You have to turn on showing all levels of menu. Follow my tips steps:

1. If you have Menu module published on "offcanvas" position, go to module settings and Sub-menu Items: Show > Save and Close

2. If you don't have any module (1), go to Template Options > Menu > Offcanvas (tab) > in Maximum Level: change from "All" to "3" > Save & Close.

Do step (2) even if you've done step (1).

Damn, I have done something wrong, now none open

At least on my Windows browser it open-close. Maybe refresh browser cache. Repeat steps.

Use also that

.offcanvas-menu .offcanvas-inner .sp-module ul > li a, 
.offcanvas-menu .offcanvas-inner .sp-module ul > li span { line-height: 22px;}

Then blog menu items (Mobile Menu) will be like that

Becuase those two menu items, are not LINKS. You used Headings (!) menu type. Yes, we informed about that in Helix documenation.

Read purple info box here >> https://www.joomshaper.com/documentation/helix-framework/menu-navigation#documentation-heading-3

I cleared browser on mobile. Now none working.. I added the nes CSS code.

as I informed in documenation, use # as link. It's a trick, becuase Joomla don't like empty space in Menu URL field.