Primefaces CommandLink only works the first time it's clicked

Question

I have a datatable, and have links that allow the user to insert a row directly below the current row. This should then update the numbering.

It works perfectly once, creating a new row, populating the number and adding one to the numbering for all rows below.

If I click anything else though, it seems as though the ajax request completes but nothing happens.

You will see that I am using the #{table} variable to get the row index of the UIData element. I have tried using process="@form" and process="@this" in the commandLink, but to no avail sadly. Likewise, my method was returning void so I set it to return a null String, but the same result occurred.

XHTML

<h:form id="feForm">
   <p:dataTable value="#{fichaExpandidaBean.feFlujoNormalList}" binding="#{table}" var="fn">
      <p:column headerText="Paso:">
         <h:outputText value="#{fn.orden}-"/>
      </p:column>
      <p:column headerText="Descripcion:">
         <h:inputText value="#{fn.descripcion}" style="width:98%;"/>
      </p:column>
      <p:column headerText="Acciones">
         <p:commandLink style="margin: 5px;" action="#{fichaExpandidaBean.agregarFilaFlujoNormal(table.rowIndex)}" update="@form">
            <h:graphicImage title="Agregar fila abajo." value="/resources/imagenes/agregarFila.png" alt="AgregarFila"/>
         </p:commandLink>
      </p:column>
   </p:dataTable> 
</h:form>

Bean:

@Named(value = "fichaExpandidaBean")
@ConversationScoped
public class FichaExpandidaBean implements Serializable {

@Inject
    private Conversation conversation;
...etc...

public String agregarFilaFlujoNormal(int row){

        FeFlujonormal fn = new FeFlujonormal();
        fn.setOrden(row + 2);
        feFlujoNormalList.add(row + 1, fn);

        for(int i = row + 2; i < feFlujoNormalList.size(); i++){

            FeFlujonormal feTemp = feFlujoNormalList.get(i);
            feTemp.setOrden(feTemp.getOrden()+1);
        }

        return null;
    }

EDIT: I don't think it's a Primefaces issue, I get the same result with the following code:

<h:dataTable value="#{fichaExpandidaBean.feFlujoNormalList}" binding="#{table}" var="fn">
     <h:column>
        <f:facet name="header">Paso</f:facet>
        <h:outputText value="#{fn.orden}-"/>
     </h:column>
     <h:column>
        <f:facet name="header">Descripcion</f:facet>
        <h:inputText value="#{fn.descripcion}" style="width:98%;"/>
     </h:column>
     <h:column>
        <f:facet name="header">Acciones</f:facet>
        <h:commandLink style="margin: 5px;" action="#{fichaExpandidaBean.agregarFilaFlujoNormal(table.rowIndex)}">
           <f:ajax render="@form"/>
           <h:graphicImage title="Agregar fila abajo." value="/resources/imagenes/agregarFila.png" alt="AgregarFila"/>
        </h:commandLink>
     </h:column>
 </h:dataTable>