I have/had a very similar issue. It does not crash when I touch the tab controller but it does/did crash when I try to add or remove view controllers from ANY tab controller. The crashing recently started. I was able to add more view controllers by doing the following. I have no idea why it worked. Xcode 13.2(13C90) Create a new macOS project. Add a tab view controller to the storyboard and add several view controllers to it. Add another tab view controller and connect it to the first tab view controller. Add several view controllers to that new tab view controller. Quit Xcode. Reopen the new project and see if you can add a new view controller to one of the tab controllers. Quit Xcode. Open the original project that you encountered the problem and see if the problem is fixed. It was for me. Again, I have no clue why this worked but if I knew why then it wouldn't be a bug... It would be a feature. Amiright? 😁 I hope this helps someone continue with their project.