I'm using `MediaCapture` API to record audio in my Windows Phone 8.1 RT app. The audio recording works fine, but the API intermittently throws `System.Exception` with the following message:  

`RecordState System.Exception: The op is invalid.` at the statement
`Windows.Media.Capture.MediaCapture.StartRecordToStorageFileAsync(MediaEncodingProfile encodingProfile, IStorageFile file)`

I haven't been able to find more about this error cause. Can anyone point in some direction?