Thumbnail issue

[GeorgeFY]

I changed the thumbnail of my story map but although it seems it is working (in Facebook for example), when posting on Twitter I get the old thumbnail. Do you know why is that?

I tried to also repost the storymap after I have changed the thumbnail but again Twitter shows the old one.

[OwenGeo]

Hi Georgios -- Where/how did you change the thumbnail? Did you do that in ArcGIS or did you update the cover of your story?