ViewCaptureToFile Transparent Background

In ViewCaptureToFIle there is a Transparent Background setting. I checked that. I saved as a PNG where the save dialog box has another Transparent Background setting. I checked that.

However, the resulting image does not have a transparent background. How do I get a transparent background?

It’s working here for me.
You can tell in the preview if the background turns into a checker board.

Are you sorted with an updated Mac V6 SR?