Weird navigation bug, with side menu, routing views won't update

Hello guys,
I am fairly new to ionic (using the 1.0.0 beta1) and Angular, and I am working on my first project, where I experience weird bugs, I cannot understand.

My app is based on the “Ionic Book” task app, described here:

Here’s the link to my app:

In my version of the task-app, the tasks are called “instances” and each instance has several “categories” in it. Each category has a title and a status.
The user can enter instances in the side menu, via the ‘+’ button. And each instance is created with some dummy categories.
The user can choose his instances and then choose a category to see its status.

To see what bugs occur, please visit my app and add a few instances with dummy titles like a, b, c. The url form may remain empty, it is not yet needed. Don’t click on a category yet. You will notice the switching from one category to another works as expected (though all instances have the same categories).

Now when you click on a category in an instance, say in instance b, the view shows the category status, with the right category title in the nav-bar. When you now click on the back button, the mess starts:

If you now click on any category, the view always displays the category title, which you clicked at first! Not the one you want to see. Also, if I now change the instance (say to instance a) and try to switch back to instance b, the switch will not be performed (the title remains a)!

I’d really appreciate your help, since I am pretty desperate right now. Thank you