Since I posted, some people have experimented with commenting or ifdef-ing out parts of the Facebook SDK. The problem is how far to pursue the transitive closure of your edits. Here is a link to a minimal set of diffs that worked for me. That is, the executable had no AdSupport or ASIdentifierManager references. https://github.com/snorrsi/facebook-ios-sdk/commit/9d69d9ab0e510359311085def696c750c345037a

Giuma is correct -- if syntactically correct code compiles and runs on the device or Simulator, then the failure of Preview is a bug, period. I can reproduce the problem in ten lines of code (not counting closing braces): struct Outer { static let hello = "Hello" // Move MyText here and Preview compiles and runs. } extension Outer { // With MyText here app compiles and runs correctly but // Preview fails with "Compiling failed: cannot find 'hello' in scope" struct MyText: View { var body: some View { Text(hello) // This does work with Preview: Text(Outer.hello) } } } struct ContentView: View { var body: some View { Outer.MyText() } } #Preview { ContentView() }