The SVG that contains the <back, menu, & next> buttons does not draw properly in Firefox. It seems like the height and width are such that it does not fit in its containing div, therefore the next button is unavailable.
Resolved. The height & width of the SVG were never set. Most browsers seem to default the size to that of its parent element. Hardcoding these metrics resolved the problem.
The SVG that contains the <back, menu, & next> buttons does not draw properly in Firefox. It seems like the height and width are such that it does not fit in its containing div, therefore the next button is unavailable.