Well, after re-enabling the workflow that we had disabled when doing our 6.3 environment sync, and then invoking it on the necessary paths, the SVGs do in fact have thumbnails and appear to work fine with drag and drop into components. Sorry, false alarm.
In our 6.3sp1 environment, SVG graphics do not show up in the asset panel while editing a page. Other file formats do. We have also seen that intermittently, folders that contain both SVG and other image types do not show any images in the ass it’s panel.
Is there a method within 6.3 to support use of SVG assets in the Assets Panel similar to how raster-format images work? Eg preview, drag and drop? Not finding anything specifically about allowing/enabling other image formats there.