This is just a small bug, but it should be easy to reproduce, and I think, easy to fix, so I thought I'd post it.

If you have the city building screen set in the mode where when you click on the build button, it zooms to the city, and shows it from directly above,  (I believe that this is an option that you can turn on or off, I have it on.)  when you are done building, it's supposed to zoom back to the isomorphic view.  If while editing the city, you accidentally click on the build button in the toolbar again, instead of on the build button in the menu where you are supposed to select what you want to build, (something that is not too hard to do,) it repeats the zoom in action, and the screen sort of flickers. At this point, the code records the flat view from above as your original mode, and when you then click on the correct build button, or even cancel, it fails to zoom back out, and leaves you in the zoomed in perspective.

I hope this was clear enough.  More simply, to reproduce the problem, just click on the build button in the toolbar, and then click it again after the build menu opens, and then cancel, or build something.  You should see the failure to zoom back out to the correct perspective.