My CSS is bootstrap.css and when I use the class, "col-md-12" for the div element to enclose a submit button, my form won't accept any click or input. I tried it with IE and Chrome.
Since that is purely frontend, HTML and CSS, it can not be a Fuel issue? Form::submit() just generates some HTML, no rocket science at all.
Bootstrap uses <button> tags, not <input> tags for buttons, so I suggest using Form::button() instead, and pass "type" => "submit" in the attribute array to indicate it's a submit button. Works fine here.