"Cannot trade with someone you are talking to"

[Arborath]

Like the title says. I can't trade with a friend or guild members ? Any idea why or how to fix this crud?

[Höllenhund]

This happens because if person talking with any of npc (market broker, quest npc, storage master). Its probably wont be changed, u just need to wait a bit when person will leave talking with any kind of npc and then trade.