That is how I had mine set up, the content of the tab view looks like it's at least positioning itself properly to where the tabs should be.
Did you try removing the class on the <ion-tabs>? Might be a long shot, but maybe some css attribute is affecting them?
Try opening the inspector to have a look at them and see if maybe either your own css styles are affecting them unknowingly or try using the same tabs classes I did: class="tabs-icon-top tabs-positive"