I have encountered this issue as well. No buttons work, the instrument panel is not available, and no collections can be created. I fixed this issue by forcing a sync after logging in. Once the existing collections and databases were able to be downloaded, the app worked as it should.
I believe that this is tied to the way the app behaves when collections are not available, and to be frank, the way it behaves right now is a bit tricky. Let’s say that I dropped my iPad and broke the screen, and now I needed to get CE installed on another device but I have really shotty internet. Downloading the App might be possible, but downloading the entire profile with the collections and tracks would be difficult. In the current configuration and the way the app behaves, I would not have a useful piece of equipment that I would hope to have available for sailing. I can see this being a bigger issue as many people start migrating to the new Mac computers with Apple sourced processors as main nav PCs, because of the compatibility between the iPad and Mac platforms.