ReproduceIssueWithCsomListItemRoleAssignments.cs

using Microsoft.SharePoint.Client;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Security;
using System.Text;
using System.Threading.Tasks;

namespace SharePointOnlineTest {
  class Program {
    static void Main(string[] args) {
      string userName = "xxxxxxx@tenant.sharepoint.com"; //give your username here  
      string password = "xxxxx"; //give your password  
      var securePassword = new SecureString();
      foreach (char c in password) {
        securePassword.AppendChar(c);
      }

      string siteURL = "https://xxxxxx.sharepoint.com/yoursitehere";
      //Create the client context object and set the credentials  
      ClientContext clientContext = new ClientContext(siteURL);
      clientContext.Credentials = new SharePointOnlineCredentials(userName, securePassword);
      //Load the web  
      Web web = clientContext.Web;
      //get all lists
      ListCollection collList = web.Lists;
      clientContext.Load(web);
      clientContext.Load(collList);
      clientContext.Load(collList, wc => wc.Include(w => w.HasUniqueRoleAssignments, w => w.RootFolder.ServerRelativeUrl));
      clientContext.ExecuteQuery();

      foreach (List oList in collList) {
        Console.WriteLine("-- List: {0} permissions:", oList.RootFolder.ServerRelativeUrl);
        var listItems = oList.GetItems(CamlQuery.CreateAllItemsQuery());
        clientContext.Load(listItems);
        clientContext.Load(listItems,
          items => items.Include(
            item => item.Id,
            item => item.DisplayName,
            item => item.HasUniqueRoleAssignments,
            item => item.Folder,
            item => item.File,
            item => item.ContentType
            ));
        clientContext.ExecuteQuery();
        foreach (var listItem in listItems) {
          Console.WriteLine("List item: " + listItem["ID"]);
          if (listItem.HasUniqueRoleAssignments) {
            if (listItem.HasUniqueRoleAssignments) {
              clientContext.Load(listItem.RoleAssignments,
                ras => ras.Include(
                    item => item.PrincipalId,
                    item => item.Member.LoginName,
                    item => item.Member.Title,
                    item => item.Member.PrincipalType,
                    item => item.RoleDefinitionBindings));
              clientContext.ExecuteQuery();
              if (listItem.RoleAssignments.Count == 0) {
                Console.WriteLine("Error: Expected to have unique permissions but couldn't find them!");
                continue;
              }
              foreach (var roleAsg in listItem.RoleAssignments) {
                Console.WriteLine("User/Group: " + roleAsg.Member.LoginName);
                List<string> roles = new List<string>();
                foreach (var role in roleAsg.RoleDefinitionBindings) {
                  roles.Add(role.Description);
                }
                Console.ForegroundColor = ConsoleColor.Red;
                Console.WriteLine("Permissions: " + string.Join(",", roles.ToArray()));
                Console.ForegroundColor = ConsoleColor.White;
                Console.WriteLine("----------------");
              }
            }
          } else {
            Console.ForegroundColor = ConsoleColor.Green;
            Console.WriteLine("No unique permission found");
            Console.ForegroundColor = ConsoleColor.White;
          }
          Console.WriteLine("###############");
        }
      }

      Console.ReadKey();
    }
  }
}