Hi tjstephens,
The titleblock should be inserted with the border at the time of drawing creation. By default, based on the units in the design (mm/in) the drawing settings should follow suit, ISO defaults for mm and ASME for in. The fact your menu item says just "Title Block" vs. "ASME Title Block" or "ISO Title Block" makes me think something is not quite right in your preferences.
Can you expand your user menu (upper right) > Preferences > Drawing, and see what your default settings are? If you always work in one Standard (say ASME with inch units) you can specify those here instead of the "Inherit From Design". If you work in a mixed environment and want to keep "Inherit from Design" as the default can you change the settings here > Apply > OK > restart Fusion, then re-launch Preferences and set to your preferred setting?
Please let me know how it goes, we've had a few reports of this in the past and a hard reset of Preferences has taken care of it.
Thanks,
Chris