captureOffscreenArea in display.save() of ScrollViewWidget appears to have no effect

I have a ScrollViewWidget with a scrollHeight greater than the widget height.  I’d like to capture the entire contents of the widget using display.save() with the captureOffscreenArea parameter set to true, but only the onscreen portion of the ScrollViewWidget is being saved.

This problem has come up before (https://forums.coronalabs.com/topic/64933-captureoffscreenarea-does-not-capture-off-screen-areas/?p=335339), but I thought it had been fixed. I’m using the latest public build (2017.3068).  Any idea why this might not be working?

By the way, the workaround I am using is to populate a GroupObject with another set of DisplayObjects identical to the ones I am adding to the ScrollViewWIdget and using this GroupObject as the first argument to display.save() with captureOffscreenArea set to true.  That works as expected:

local \_g = display.newGroup() -- Populate \_g with DisplayObjects identical to those in the -- scroll view, but NOT the same objects (this would remove them -- from the scroll view). display.save( \_g, { filename = "foo.jpg", baseDir = system.TemporaryDirectory, captureOffscreenArea = true })