Hi , 

I have the same problem and I found that if the last lookup has more than about 400-500 items to filter if failed. Now I will try to ask help desk if it's a feature or how can we solve it.

Hello Ivan,

We have identified the issue, and it has nothing to do with the numbers of levels of cascading lookups.  What we've found is that if a list as a large number of items and there are indexed columns, the dropdown in the form becomes blank.  We don't know what the max limit on the items is before this issue occurs.  We were able to workaround it by removing the indexes on the columns.  We are currently on version 2.9.1.20.  I am not sure if this was resolved in the future versions.  Looking at the release notes, I did not see this issue mentioned. I have opened up a ticket with Nintex support.  We are indexing columns to prevent orphaned lookup entries. Hopefully, this will be fixed in a future version. 

Regards,

Maureen

Hello Maureen,

you did it with a script like this?:

Add-PSSnapin Microsoft.SharePoint.PowerShell -ErrorAction SilentlyContinue

$site = Get-SPSite -Identity "SiteCollectionURL"

foreach ($web in $site.RootWeb.Webs)
{
   $list = $web.Listst"Pages"];

   $field = $list.Fieldse"ColumnName"];
   $field.Indexed = $false;
   $field.Update();


  Write-host     "Article Author Deindexed on" $web.URL
     
}‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Hello Ivan,

You can use a script.  I just went to the list settings, and clicked on Indexed Columns under the Columns section.  You will see the columns that are indexed.  From there you will be able to click on the column name that is indexed and delete it.