Unstickiness

I've created a menu block at the left, incorporating a logo. I want the sticky navigation effect to turn the menu system into a horizontal bar that contains the logo.

I've done all this, but the sticky effect isn't working. The navigation system stays in one block when I scroll instead of turning into the menu bar. What am I missing?

I've hidden the header and tagline. I'm using the following code in my child theme to hide the header.

.site-header {
    display: none;
}

Here are my Primary Navigation Layout settings.

Mobile menu label: Menu
Navigation width: Full
Inner navigation width: Full
Navigation position: Left sidebar
Navigation alignment: Left
Navigation dropdown: Hover
Navigation search: Disabled
Sticky navigation: Both
Sticky navigation effect: Slide
Navigation logo: [uploaded and selected]
Navigation logo position: Sticky + static
Slideout navigation: Disable
Primary menu items: 20 left/right; 60 height
Sub-menu item height: 10

Here are my Secondary Navigation Layout settings.
Mobile menu label: Menu
Navigation width: Full
Inner navigation width: Full
Navigation position: Left sidebar
Navigation alignment: Left
Primary menu items: 20 left/right; 40 height
Sub-menu item height: 10

WP 4.7.1 running locally under MAMP 1.9.6 with PHP version 5.3.5. I'm using a child theme based on GeneratePress 1.2.41 with version 1.2.92 of the GeneratePress Premium plug-in.

Just a note: BTW, the order of the Primary Navigation options in the Navigation Width and Inner Navigation Width drop-down menus is reversed. Same two options but listed differently.