rails / using let does not save the record

Give the below simple example :

let(:item) { create(:item }
it 'query by scope' do
  expect(Item.all.length).to eq 1
end

The test does not pass.

Adding item.save within the it block, the test pass. Using a before(:each) { create(:item) } instead of let make the test pass too.

Sounds obvious, as the point I might be missing, why is let not effectively creating the record in this case ?