When viewing groups in the premade group finder for Nerub-ar Palace’s Heroic difficulty and mousing over the group to see details, the leader’s list of normal difficulty bosses defeated is displayed. This is very easy to verify by logging on to a character with any normal bosses down, listing your own group for Heroic, and then using the Browse Groups button to go find your own listing. It’s a very annoying display bug since it makes listings fairly confusing and all group leaders have to constantly update their titles if they are leaving their group listed and have cleared the normal version of the raid. I couldn’t figure out why every single group leader seemed to have already cleared the raid, until it hit me that this was the cause.
This only applies to listed groups for Heroic. Posting a listing for Mythic does not incur the issue, as it correctly shows no bosses down for me when I test it.