I've faced the same issue. Since (at least) Xcode 16 release debugging performance has been drastically degraded, many unobvious errors are persisting in the error logs like this: SwiftASTContextForExpressions(module: "ModuleName", cu: "MyFile.swift")::MyMethod() -- Missing Swift module or Clang module found for "ModuleName", "imported" via SwiftDWARFImporterDelegate. Hint: Register Swift modules with the linker using -add_ast_path. as well as other types of errors mentioned by people above. And nothing, even swift healthcheck "hints" couldn't help with it.

Encountering the same issue on Sonoma 14.6.1 (23G93) and Xcode 16.0 (16A242d). Seems this one is more like Xcode-related. As for me it sometimes get fixed after navigating through code using "steps" (step over/step into, etc.) and attempting to print object one more time, even after such error. Report after running swift-healthcheck in lldb contains such errors like: SwiftASTContextForExpressions(module: "ModuleName", cu: "MyFile.swift")::MyMethod() -- Missing Swift module or Clang module found for "ModuleName", "imported" via SwiftDWARFImporterDelegate. Hint: Register Swift modules with the linker using -add_ast_path. Seems like suggested hint could solve the problem, but before upgrading to new Xcode I didn't have such issue.