I installed beta 3 and after it opened the project I had been editing with beta 2.2, I got an error indicating that there was no class for my root model in my sandbox. When I tried opening the model, I only saw <abstract model>. I tried re-opening the project in beta 2.2, and saw the same issue. Fortunately, I had everything in source control and I was able to revert all changes. Konstantin, if you're looking into this, you should be able to recreate the issue using the project I sent to you over the weekend.