Some friends not appearing online in in-game lobby.

Hi everyone, As the title says, I am having trouble seeing some friends online in the in-game lobby. I am on an Xbox Series X. I have a couple of Xbox friends that I haven't been able to see online in the Destiny in-game lobby for years now, either in the Bungie friends list or the clan list. Some friends I can sometimes see online there and other times they do not appear. What is odd is that I can be in a party with other friends who can see them online, some on Steam, Xbox or PS. Also odd is that I can see them on-line in the D2 Companion app. Is anyone experiencing this and know why it is happening ?