Seeding before Rails feature test

I have a number of feature tests which rely on a fair amount of data being in the database. I have put this data in a seed file and am trying to call it in the before block in my tests

feature 'capybara tests' do
    self.use_transactional_fixtures = false

    before do
       DatabaseCleaner.strategy =:truncation
       DatabaseCleaner.clean
       MyApp::Application.load_tasks
       Rake::Task['db:seed:capybara'].invoke
    end

    scenario 'one' do
    end

    scenario 'two' do
    end
end

The above doesn't work. Scenario two has an empty database. The before block is being called just before running scenario two, but the seed rake task is silently not executing so I'm left with an empty database.

Can someone tell me why this is happening and how to fix it? Thanks