Hi ographix,
I’ve read through this thread and based on what I’m seeing, my guess would be that one of the plugins you have installed is playing games with the ordering. If the Media Library is not retaining the order you set then whatever is preventing that is likely also the root of DG not giving you the order you want.
Would you mind doing a test for me? First, disable all of your plugins except DG. Then, go and modify the order of the attachments in the media library, close, then re-open and see whether their new order is retained. If it is, then DG should also work.
Assuming the above works, you’ll next need to re-enable the other plugins one-by-one, each time doing the same test until it stops working. Whichever plugin you most recently activated after it stops working will be the culprit.
It is also possible, though much less likely, that the theme you are using is doing something incorrectly so if the above does not work then the next step would be to disable all plugins except DG and also switch your theme to Twenty Fourteen or Twenty Thirteen and repeat the same tests described above.
If all of that doesn’t result in you being able to order your Media Library then we’ll have to keep working on it.
-Dan