Appian 22.1 Portal: Is there a limitation in Appian Portal that we can't use a background media(as document image) in billboard layout?

Certified Senior Developer

Appian 22.1 Portal: Is there a limitation in Appian Portal that we can't use a background media(as document image) in billboard layout? I am trying to publish a portal with billboard layout that has background media (document image) . However, portal is not getting published and throwing an error. When i remove the image from billboard layout, portal is getting published. Is there any limitation to portal or am I missing something here? 

Note: document image is working in image field

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