dispose() not working?

[TakeOwer]

Hi,
I implemented this "very useful" library in one of my projects. When I run the player of a file and after stopping it, if I want to delete it from the list it does not delete it. It gives me a message that the file is in use by the program... despite the call to the following code:
_soundOut?.Stop(); _soundOut?.Dispose(); _source?.Dispose(); _pitchShifter?.Dispose(); _soundOut = null; _pitchShifter = null; _source = null;

Is there a solution to release the library so that the file is not in use by the program?
Thank you in advance for any solution you would like to suggest 😊
Best Regards
Salvo