One menu follows active, another does not

Please see the attached files for the settings of the Menu Blocks I'm working with.

Assume this menu:

Thing 1
...Thing 1.1
...Thing 1.2
......Thing 1.2.1
.........Thing 1.2.1.1
.........Thing 1.2.1.2
...Thing 1.3
Thing 2
...Thing 2.1
...Thing 2.2
...Thing 2.3
Thing 3
...Thing 3.1
...Thing 3.2
...Thing 3.3

• The intent of "Quick Links" is to display all and only links that share the same menu level as the page we are currently on.
• The intent of "Related Content" is to display all and only links that are children of the page we are currently on.

If we are on page 1.2:

• Quick Links should show 1.1, 1.2, and 1.3.
• Related content should show 1.2.1 as well as 1.2.1.1 and 1.2.1.2.

Related content seems to be working just fine, but Quick links seems to just stay static the entire time, only showing the actual second level of the menu and nothing more, even though "Make the starting level follow the active menu item" is checked. It even just plain disappears if you go deep enough in the menu. While Related Content should certainly disappear when there are not child items to display, Quick Links should always show up because there will always be siblings of a menu item, even it it's just itself.

What am I doing wrong?

Thanks, in advance, for any assistance you can provide.