Hello there,
we are using AX2012 with enterprise portal.
When trying to select multiple record on list page, the page immediately shows issue below.

After selecting the second record, the EP page shows error below.

This happens on every EP list page. And below is the details found in event log.
We have tried to refresh AOD, element and data dictionary. Generate full CIL after deleting XPPL files, redeploy EP web site and restart AOS but the problem is still there.
What else could we try? Many thanks.
An unexpected error has occurred.
Index was out of range. Must be non-negative and less than the size of the collection.
Parameter name: index
System.ArgumentOutOfRangeException
at System.ThrowHelper.ThrowArgumentOutOfRangeException(ExceptionArgument argument, ExceptionResource resource)
at System.Collections.Generic.List`1.get_Item(Int32 index)
at Microsoft.Dynamics.AX.Framework.Portal.Data.DataAccessObject.AxDataAccessObjectView.<SetSelectedRowIndices>b__1c(Int32 rowIndex)
at Microsoft.Dynamics.AX.Framework.Services.Client.EnumerableExtensions.ForEach[TItem](IEnumerable`1 enumerable, Action`1 action)
at Microsoft.Dynamics.Framework.Portal.UI.WebControls.AxGridView.HandleMarking(IReadOnlySet`1 markingIndexes)