Apparently one cannot import an app from Web AppBuilder in ArcGIS Online to Web AppBuilder Developer edition since the developer edition is a version older than the Integrated version in ArcGIS Online. When will the developer edition be updated to that of the Integrated ArcGIS Online version to allow importing of apps from my account?
Yes, in theory it should work for the next WAB developer edition update. The typical order is ArcGIS Online, then the developer edition about 4-6 weeks later. Portal goes on a different schedule.
It will be posted when it is out, or you can follow me /blogs/myAlaskaGIS/2016/03/09/web-appbuilder-developer-edition-customization-resource-list post since I typically update the page as soon as I see something (but I am a user too, not staff).