Windows 10 (64 bit)
I have just been experimenting with saving objects and realised that when I select 'Save Objects to File ' from the Objects menu it saves all objects currently on screen, not just those selected, which was the behaviour I had expected.
As I was creating a fairly complex edit of a screenshot I decided a small open circle would suit for both the current screenshot and others in the future, so I deselected all objects, selected the small circle alone and 'saved objects'. I was then surprised to find when I loaded what I thought would be my lone small circle that all the objects from the previous screenshot that I had deselected had been saved together with the wanted circle.
If this is the intended behaviour of this feature then I can live with it and work around using a second instance of Greenshot for creating single objects to save on-the-fly. Alternatively if it is not the expected behaviour I shall either convert this to a bug report or raise a separate bug report for it.