A couple of things – the most important is that when you have a debug question, it’s also necessary to show the entire output from OELogging as explained here: https://www.politepix.com/forums/topic/install-issues-and-their-solutions/
But the approach of loading a recorded file into an AVAudioRecorder instance and then referencing it from that instance’s URL doesn’t really make sense to me – the method is expecting a string which is the path to an already-completed and closed file which is a 16-bit, 16k mono WAV. The code you’ve shown doesn’t suggest that that is what is being passed to the method. It just looks like it can’t open and read the contents of the path, which is what I’d expect in this case. Just go ahead and pass a path to a completed and closed WAV file with the right format to the method, and skip the indirection or breakage that the AVAudioRecorder instance is causing.