Modification of a standard field changes it to a virtual field

Good day everyone, 

We have a changed the description field of the OwnerID (standard field) and changed the description field to use our usrCustomName field like this:
 

[PXNonInstantiatedExtension]
public class CR_CROpportunity_ExistingColumn : PXCacheExtension<PX.Objects.CR.CROpportunity>
{
    #region OwnerID  
    [PXDBInt]
    [PXMergeAttributes(Method = MergeMethod.Append)]
    [PXCustomizeBaseAttribute(typeof(OwnerAttribute), "DescriptionField", 
                              typeof(MAKLBAccountExt.usrCustomName))]
    [PXSelector(typeof(Search<EPEmployee.defContactID>),
                    typeof(EPEmployee.acctCD),
                    typeof(EPEmployee.acctName),
                    typeof(BAccountExt.usrCustomName))]
    public int? OwnerID { get; set; }
    #endregion
}

The changes we made is on the CROpportunityExt DAC.

The problem we face now however is that we get an error on the Generic Inquiries

and the DAC Schema also displays this:

If I unpublish this, it works. 

Has any one ever experienced this and if so, how did you get around this? Is there something I did wrong in the code? 

Thanks in advance.