Discord.NET GetUser returns null

Question

When I try to pass a ulong discordId through await user.AddRoleAsync(role), I get the error that Object reference not set to an instance of an object, meaning that user is null.

I have tried

 private async Task GiveRoleAsync(DiscordSocketClient client, ulong discordId, SocketGuild guild)
        {
            try
            {
                if (!string.IsNullOrEmpty(discordId.ToString()) && guild != null)
                {
                    Console.WriteLine(discordId);
                    var role = guild.Roles.FirstOrDefault(x => x.Name == "Acolyte");
                    var roleId = role?.Id;

                    if (role != null)
                    {
                        var user = guild.GetUser(discordId);
                        if (user != null)
                        {
                                await user.AddRoleAsync(role);
                        }
                        else
                        {
                            Console.WriteLine("User not found in the guild.");
                        }
                    }
                    else
                    {
                        Console.WriteLine("Role not found.");
                    }
                }
                else
                {
                    Console.WriteLine("User or Guild ID is null.");
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.ToString());
            }
        }

However, I always receive the error that "User not found in the guild.", even when manually inserting my own discord id via the client. As a note, I am trying to gather discordIds from a database and update roles according to certain parameters, and Console.WriteLine(discordId) works, but Console.WriteLine(user.Id) prints null. Additionally, I have the Server Members Intent enabled as I am able to do something very similar using a select menu.

private async Task GrabRolesHandler(SocketMessageComponent arg)
    {
        try
        {
            if (arg.User != null && arg.GuildId != null)
            {
                var text = (arg.Data.Values);
                var userId = arg.User.Id;
                Console.WriteLine(userId);
                SocketGuild guild = _client.GetGuild(arg.GuildId.Value);
                var role = guild.Roles.FirstOrDefault(x => x.Name == text);
                var roleId = role?.Id;
                
                if (role != null)
                {
                    var user = guild.GetUser(userId);
                    if (user != null)
                    {
                        if (user.Roles.Contains(role))
                        {
                            await user.RemoveRoleAsync(role);
                            await arg.RespondAsync($"You have **disabled** pings for the <@&{roleId}> role", ephemeral: true);
                        }
                        else
                        {
                            await user.AddRoleAsync(role);
                            await arg.RespondAsync($"You have **enabled** pings for the <@&{roleId}> role", ephemeral: true);
                        }
                        
                    }
                    else
                    {
                        Console.WriteLine("User not found in the guild.");
                    }
                }
                else
                {
                    Console.WriteLine("Role not found.");
                    await arg.DeferAsync();
                }
            }
            else
            {
                Console.WriteLine("User or Guild ID is null.");
            }
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex.ToString());
        }
    }