As stated in the title, you should "work again" on scoreboardManager, which results in these errors with the following codes:

Using

player#getScoreboard

• It causes the player to get a scoreboard, so if there is another scoreboard plugin, the scoreboard will not work properly, not all players will see the set of prefix.
• In some cases it will breaks also the sort-priority what the user set.

To reproduce:

Create a method that has a player for-loop create a field in it, this field has the player#getScoreboard method, then set prefix/suffix settings (and those needed to create another team), finally use the player#setScoreboard method to set the scoreboard. Then install any scoreboard plugin (made with a NO reflections packet) and start the server with the plugin created. Log in to the server with two accounts and the result is here.

public void setTeam() {
    String name = "10001MyGroup"; // Group name with priority
    String name2 = "10002OtherGroup";

    for (Player player : Bukkit.getOnlinePlayers()) {
        String g = name;
        if (!player.hasPermission("perm.mygroup") &&
              player.hasPermission("perm.othergroup")) {
            g = name2;
        }
 
        Scoreboard tboard = player.getScoreboard();
	Team team = tboard.getTeam(g);
	if (team == null) {
	    team = tboard.registerNewTeam(g);
	}

        team.setPrefix(g.equals(name) ? "MyGrouppref" : "OtherGrouppref");
	team.setSuffix("anotherPrefix");

	team.setColor(ChatColor.RED);

	if (!team.hasEntry(player.getName())) {
	    team.addEntry(player.getName());
	}

	player.setScoreboard(tboard);
    }
}

There is still a small modification to this, but it is understandable.

Using

Bukkit#getScoreboardManager#getNewScoreboard

• This causes you to create a scoreboard, but it doesn't do the right thing:
  • Other scoreboard plugins will work with the tablist prefix, but the sort priority will crash, so it will not be sorted, but by default in a-b-c order.
• The other issue with this is that if you create a scoreboard in the class instance (to avoid a lot of scoreboard) and use it with players in a for-loop, the scoreboard will start showing both players ’scoreboard to everyone, which will become a flick.

To reproduce:

The same code that is on top, only Scoreboard is outside that method and Bukkit#getScoreboardManager#getNewScoreboard is specified.

And if we uses the Bukkit#getScoreboardManager#getMainScoreboard method, it will not work.

These issues can be tested with the following plugins:

• [TabList|https://www.spigotmc.org/resources/46229/]

• • Related github issues: #127, #124
• AnimatedScoreboard

There is no screenshot because it is proven and I get this kind of error almost on a daily basis.

With Java reflections, they work properly.