Back button labels

The app I’m working on was built with a series of screens for the user to fill out before submitting the order (i.e. it’s a wizard). The screens share the same controller and the button to advance to the next screen calls the same function with the parameter name of the next screen. The controller code looks like this:

function nextView(state) {
  $state.go('app.consumer.create-job.' + state);

For the first two screens in the sequence the back button in the header is labeled with the name of the previous screen’s view-title. After screens the label changes to Back and stay that way for the rest of the sequence. I don’t see any difference in the code between the different screens. All of the ion-views have view-title set. Is there somewhere else I should look? Could this be an ionic bug?