Getting the same issue. Blizzard-App/BNET-App seems to be reasonable, since Bungie moved to Steam-servers, so there no longer seems to be chat-traffic available over the former Blizzard ones. Not reasonable is the Bungie.net-website when you click a profile and type then, except for, the reason would be, i log in with Blizzard-Account instead of Steam (haven't tried yet). Opposing to this Impression is the fact, that i can log in with Blizzard-account and type in clan-chat. There also are PM and clan-issues in game, like on Tower you can see the randoms and their info, but not your own clanmates ones, except for, you take the workaround to add them as Steam-friends. On your topic, attempting to log in with Steam-account might work, if not already done, because i know, i only tried Blizzard one...guess out of a habbit. :D Also your recipient needs to have migrated to Steam, i guess.