Missing ID numbers from the CSOM PS script

Hello,

Thanks to the quick and helpful responses I have been getting here I have been able to make a CSOM PS script to pull data from an external list and save it as a CSV file. Data is getting pulled regularly and all was well until 

I had to start pulling the external list’s ID number. I’ve added that to my powershelgl script and I seem to be getting almost all of the ID numbers of the 1500+ items except for a few items that give me either a ‘5’ or ‘blank’ I cannot explain this because when I view the list itself, I am able to see all the ID numbers.

Also, as a test I modified my script to pull only the ID numbers to only get the same results. I’m hoping someone can shed some light on this issue I am facing. Below is the script I am using where the outcome is a CSV file that

gives me the ID numbers and the Title of each item from the external list.

Function Get-SPClientList {
param (
$uri,
$list
)

$cSharp = @"
 
using System;
using System.Collections.Generic;
using Microsoft.SharePoint.Client;
 
namespace SPClient
{
    public class SharePointList
    {
        public static ListItemCollection GetList()
        {
            ClientContext clientContext = new ClientContext(`"$uri`");
            List list = clientContext.Web.Lists.GetByTitle(`"$list`");
            CamlQuery camlQuery = new CamlQuery();
            camlQuery.ViewXml = "<View/>";
            ListItemCollection listItems = list.GetItems(camlQuery);
            clientContext.Load(list); 
            clientContext.Load(listItems);
            clientContext.ExecuteQuery();
            return listItems;
        }
    }
}
"@
 
$assemblies = @(
    "$PSSCriptRoot\Microsoft.SharePoint.Client.dll",
    "$PSSCriptRoot\Microsoft.SharePoint.Client.Runtime.dll"
    "System.Core"
    )
Add-Type -TypeDefinition $cSharp -ReferencedAssemblies $assemblies
 
$items = [SPClient.SharepointList]::GetList()

$out = @()
foreach ($item in $items) {
    $obj = new-object psobject
 
        foreach ($i in $item.FieldValues)
        {
            $keys = @()
            $values = @()
            
            foreach ($key in $i.keys) {$keys += $key}
            foreach ($value in $i.values) {$values += $value}
            
            for ($i = 0; $i -lt $keys.count-1; $i++)
                {
   
   if(($keys[$i] -eq “ID”) -or ($keys[$i] -eq “Title”))
   {
    $obj | Add-Member -MemberType noteproperty -Name $keys[$i] -Value $values[$i]
   }
  }
       }
        $out += $obj
    }
    $out | Export-CSV "D:\Install\scripts\ExternalList.csv" -NoTypeInformation  

####This is the end#####

}

Get-SPClientList('http://externalsite/sites/site1/', 'ExternalList')