I don't know about other systems, but in-game chat is seriously broken on Xbox One.

(1) Upon joining a group, we are automatically and involuntarily moved from our current chat channel to group chat. This may be an intended "feature", but it is an awful one that nobody wants and is undesirable ~95% of the time. We can do it ourselves when desired, so stop changing our channel automatically!
(2) When fixing this unwelcome disruption and returning to the desired guild chat channel, the guild channel frequently (~10% of the time) simply disappears entirely off the list of available channels. Selecting another guild channel usually makes that channel disappear, too. Sometimes we can get into channel 3 or 4 if we're lucky.
(3) When in group chat, traveling to another zone frequently (~25% of the time) kicks us out of voice chat entirely, leaving us with no active channel.
(4) I haven't personally seen this bug in a while so it may have already been patched but I'll mention it here just in case: when changing channels (either involuntarily or voluntarily) we are often trapped in a loop where the channel fails to change, then tries again 5-6 times before finally successfully changing to the new channel.

These annoyances really disrupt the social element of the game and fixing them should be a high development priority for an MMO.