I saw this annoying bug for the first time today. The issue: Could not drag an image from Skitch to another app (tried Slack and Gmail). When the image was dropped, it was simply a white image with the name 'Blank.jpg'. The solution: In Skitch: Take a screenshot and insert an annotation (I created a Skitch annotation Box). Delete the annotation. Drag your image to an outside program. This seems to have resolved the issue for the time being.