I use the Destination Atop blend option to highlight key areas in some of my maps, this is really effective at focussing the user in a story. As of the latest update, regardless of the background setting within a map, StoryMaps is not "accepting" the setting. For example, all my maps are set to have a white background, however, when placed into a StoryMap (as of latest update) the background is shown as grey. The maps, in map viewer, display as expected.
This issue has also cascaded through previously created maps within StoryMaps - most of these stories are published publicly so this directly affects the intended user experience.
I do use custom designed Themes, but these are very simple black on white themes with org logo and colour divides.
The following, as an example, was perfectly white a couple of days ago - and now, without editing - it's changed. (btw - this behaviour can also be seen in Portal 11.0)
