You can first try to make it submit with simple html (without Form facade). By the way you don't have {!! Form::close() !!} in your example. See if you have it in modal.

Thanks - got it working now, but I see I have the same problem others have posted about: When you submit the form it takes you back to the main page rather than display a correct or incorrect login message on the login form. From what I've seen to keep the form open after submit I either have to use Ajax to submit the form, or an iframe. Any advice on how to keep it open?

If you want to submit the form without page reloading ajax will be a good way to do that.