Why aren't the navigation arrows showing for my slider?

When using the slider layout, the Section content alignment setting has to be set to Full Width for the navigation arrows to display properly

For any module that has a slider layout, the module needs to be added to a 1 column section with no other modules in the same section and the content alignment needs to be set to Full Width.

While the Section has to be set to Full Width, you don't have to check the Full Width option in the module Layout settings unless you want the slider to be edge-to-edge in the browser.