I can provide an image of the issue (see link: https ://ibb.co/NL33L11), but will need some assistance locating the version information. Per the image, you can see a scroll bar to the right of the Site Navigation item (labelled in Studio -> Navigation -> Menus -> Site Navigation). Does this help clarify my issue?

It's completely different issue. Most probably you've updated to UNA 12.0.0-B1, you can see system, version in Studio > Dashboard and modules versions in Studio > Apps Market. To resolve the issue check if you have outdated modules in Studio > Apps Market > Updates. If it don't help, then you need to update your custom templates styles mix, I suggest to create new style mix based on default one and make appropriate changes.