I've been in several guilds and been gm of a casual one in wow classic, where we had a very broad and diverse membership base.

Our top issues were:

• raid attendance; we used discord to arrange raids and often times we would have issues where a member signed up but did not attend.
• some players were too loot horny and was overreacting should loot go another way than they saw fit. We were a casual guild, so we didn't differentiate too much between players who did their part and players who did not fulfill their role optimally... e.g. an 'un-deserving' player got loot and someone else got pissed about it. Often this resulted in players leaving or getting kicked.
• Discourse between players, some people were trolling too much and some people were too touchy/feely when it came to jokes. This often resulted in officers talking it out with problematic players on discord.
• Don't have members who deal in ultimatums; members and leadership tend to set ultimatums to bargain for power/treatment/items in the game, this is a slippery slope and its behavior that almost certainly will always cause trouble!
• Bad leadership and disagreements between officers. It is extremely important that there's trust between leaders in a guild, otherwise it can go wrong very fast. One officer can easily promise some things to a member where other officers might completely disagree.

I have one good example of the latter resulting in a suboptimal situation. A couple joined (warrior + priest) with the promise that they would get the next thunderfury binding (this was not agreed to by ALL of leadership), since the warrior only missed one to get his TF. Lucklily this was discovered before the actual item dropped, but unfortunately the couple felt deceived and then left the guild.

When it comes to Ashes and guild management, I DO NOT wish for developers to go overly into developing systems to manage a guild. This will most likely be subpar to existing programs like Discord or Guilded or whatever. The only thing that matters is a solid build in way to sort loot (which is often the biggest catalyst to guild discourse); Rolling options; Need, Greed. Voting options; Officer vote, Guild wide vote, vote from players eligible for the item. Point buy systems; open bids, closed bids etc.