Yes, that happened for me as well. Also the opacity, trim etc modifiers does not work! This happened when I updated from Xcode 12.0 to 12.1. Everything was working perfectly before the update. I had to redesign my widgets and take away some functionality. Really disappointing! However, I read somewhere on this forum that macOS Big Sur may solve these problems. Haven't tried the beta myself so I can't verify it. Edit: Found the other thread https://developer.apple.com/forums/thread/665685

I've got the same problem and also found a solution (well at least kind of). This problem is very easy to reproduce on my Mac Mini M1 and Xcode 12.3. Create a new UIKit project Create a custom component class (e.g. like the code below) Add a UIButton to your main ViewController In the Identity inspector, change the button class to your custom component Now the custom component will not be rendered in the IB and you will find an error message in the Issue Navigator. The only way to have it rendered is to change the build setting "Build Active Architecture Only" for Debug to "No" (instead of the default "Yes"). Now the custom button is rendered correctly in IB without the error message. Instead you get another message suggesting to revert to recommended settings. I have not encountered this problem on my MacBook Pro (Intel processor) so I guess this is only related to the M1 and the IB. import UIKit @IBDesignable class CustomRoundedButton: UIButton {          override init(frame: CGRect) {         super.init(frame: frame)         commonInit()     }     required init?(coder aDecoder: NSCoder) {         super.init(coder: aDecoder)         commonInit()     }          override func prepareForInterfaceBuilder() {         commonInit()     }     private func commonInit() {         self.clipsToBounds = true         self.layer.cornerRadius = self.bounds.size.height / 2     } }

@Claude31 Yes, I see that you are using Catalina which means that you do not have a M1 Mac. This issue seems to be related to M1 Macs only.

Well at least you can open the Settings app... I also installed Xcode 15.0 and my Settings app crashes immediately when I try to open it when running an iPhone 15 Pro simulator with iOS 17.