This is typically caused by a channel not including the legacy poster artwork references in the manifest, and the artwork they refer to.
Make sure you have these in your manifest file:
mm_icon_focus_hd=pkg:/images/icon_focus_hd.jpg
mm_icon_side_hd=pkg:/images/icon_side_hd.jpg
mm_icon_focus_sd=pkg:/images/icon_focus_sd.jpg
mm_icon_side_sd=pkg:/images/icon_side_sd.jpg
Make sure they are pointing to a real image - it can be a small blank image if you want, since nobody will see this artwork. Also make sure there is a blank line at the end of your manifest file. Package and update the channel and the issue should be resolved for most people within 24 hours, or sooner if they force check for updates.
edit: obviously a public channel update will take longer to go live
- Joel
