Hi Kevin, Thanks for your thorough answer. I've added the print("Exiting") line and is not showing up. This is exactly what I expected. I think the program/debugger hangs on loadFromPreferences. When I pause program execution it shows a thread containing CFRunLoopRun. Same goes for the semaphore example I've provided. The program does not return/completionhandle on loadFromPreferences. Pausing program execution shows semaphore_wait_trap. What am I trying to achieve: Install/Enable a content filter from code. I would expect a popup showing up once I call the savePreferences function, but my code does not get to that line. NOTE1: I've also tried wrapping the loadFromPreferences within a DispatchQueue.main.async without success. NOTE: I've also tried the async variant of loadFromPreferences without success.