Unable to access a field in interface using rv! domain, shows [unnamed]

Hi 

I am using a recordActionField as link in one of my interfaces. To open the form on click of that link as modal window, I am using the related action. 

When I try to show the current value of that field in related action "Display Name", in the interface, it shows me [unnamed] for most of the records and for some it shows value, though every record has value for that field. 

If I use the same related action and pass other fields of same table in Display Name using rv!record[], they are displaying completely correct.

Can anyone help what can be the root cause.

Screenshots attached:

              When using rv!record[recordName.A] field creates unnamed issue

When using rv!record[recordName.B] field but works completely fine here