Sales Quotes Unit Price gets nulled after populating Customer field on the header

Hi everyone,

i’m facing a problem when i populate the Sales quotes lines from an imported file, everything is working fine when the lines were populated, but when i choose a customer from the header field, the fields returns zero for all the rows : 

and after choosing a customer:

 

i tried to use RowUpdated to get the old values back if the new value is 0 : 
 

public static bool IsActive() => true;
protected virtual void _(Events.RowUpdated<CROpportunityProducts> e)
{
     var nR = e.Row;
     var oR = e.OldRow;

     var nUnitPrice = nR.CuryUnitPrice;
     var oUnitPrice = oR.CuryUnitPrice;


     if (nUnitPrice == 0)
     {
         nR.CuryUnitPrice = oUnitPrice;
     }     
}

the code works fine, but the Ext Price is still showing 0, and automatically the Amount field also:
 

Any thoughts?