Input tags in ng-repeat stopping form submitting when enter key pressed

I have a fairly simple form like this

<form name="{{vm.formName}}">
    <input name="emailAddress" type="text" ng-model="s4pDataForm.emailAddress" />
</form>

This works fine and the form submits when you focus the textbox and hit the enter key (I am binding a function call to the submit event using another directive not shown here instead of using ng-submit).

The problem comes when I try to dynamically create the input boxes inside an ng-repeat.

<form name="{{vm.formName}}">
    <input name="emailAddress" type="text" ng-model="s4pDataForm.emailAddress" />
    <div ng-repeat="control in vm.layout.controls">
        <input name="field-{{control.name}}" type="text" ng-model="vm.fields[control.name]" />
    </div>
</form>

The form renders perfectly. I can add dynamic validation, the model is wired up correctly etc. However the form only submits when I press the enter key if the first input is focused (the one outside the repeater). If you are focused inside any of the dynamically created input fields then it doesn't submit.

I've been banging my head against a brick wall for the last hour. My original dynamic form was huge but I've got it down to this minimal test case and it makes no sense. I can only assume that because the controls are dynamically added they are not considered part of the form by the browser so they can't submit the form?