File Media Output Capture Crashes on OS X

On OS X, image frames output in PIE but crash occurs in standalone mode; The .wav file is written but is empty (the media player does not seem to go to the master submix correctly) and it seems to buffer oddly. Stopping the record on the .wav file can also lead to a crash when exiting the game, which I suspect is related to why media player is not being output to the .wav file (where sound2d works fine).

Using file media output in a blueprint to capture the current viewport, provided the viewport is a window, works well from the Editor, but crashes when run in standalone as soon as media capture is engaged.

Results:
Editor crashes when playing in standalone window.

Expected:
As with the in-editor run, it should save a series of PNG files into the media output folder.