Just passed the test, as I ran into the same problem. The tools showed a leak at the beginning of the application when the sound was played using AVAudioPlayer. It was registered only once at the beginning. Sounds created subsequently did not leak further.
When I ran the same version of the application on my iPhone using tools, there was no leak at all.
I am running iOS 11.2.5 and Xcode Deployment Target - 11.0
This seems to be just an Xcode bug, but could be related to MacOS.
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