Your Sections list in the Blueprint Forms library may appear as a blue line or thin white box because there is a display issue on your workstation and the dimensions of the sections list may be having difficulty manifesting properly in the browser.
One quick step to help resolve this is to do the following:
1. From your Internet Explorer browser, click the gear icon at top right
2. From the menu that appears, scroll down and hover over 'Zoom' > Click 'Zoom out'
3. Continue clicking 'Zoom out' until you see the list of Sections appear