Time: Ever since Early Release - I don't remember this happening in P4 or P3.
Frequency: Intermittently, often when I am alt-tabbed away from the game.
World name: Excalibur
Character name: Vhai'a Ashkhe
Area and coordinates: Limsa Lominsa, by the Aftcastle
Steps:
1. Spoke with the Calamity Salvager in LL. (Didn't notice it happening before this.)
2. When I alt-tab away from the game, and even sometimes when I have the window focused, the General chat tab doesn't update when people say things.
3. If I say something myself, or scroll my mouse wheel in the General chat pane, it automatically updates and scrolls all the way to the bottom of the chat pane. It's kind of obnoxious if there's been a lot of scroll to read through!