primefaces rowexpansion not updated - jsf

Question

I have an issue with primefaces to update a dataTable. The problem is, that after submiting the "change" button, the datatabel is not updated - not with ajax=false, not with update=... . Maybe anyone has an idea?
Note: button and datatable are in two different forms, but should not be a problem, works for another case in my project. And userOrders are loaded lazily, but i logged the list in bean, the data is correctly available.
<h:form rendered="#{orderModel.positions.size() > 0}">
<p:commandButton icon="fa fa-edit" value="change" update=":table:orderDT, temp" action="#{orderModel.editOrder()}" rendered="#{orderModel.posChecked and orderModel.orderEditable}"/>
</h:form>
<h:form id="table" >
<p:dataTable id="orderDT" rendered="#{orderModel.user.orders.size() > 0}" reflow="true" var="order" value="#{orderModel.userOrders}" selection="#{orderModel.tempOrder}" selectionMode="single" rowKey="#{order.id}" scrollable="true" style="margin: 20px">
<p:ajax event="rowSelect" update=":table" listener="#{orderModel.onRowSelected}"/>
<f:facet name="header">
Getätigte Bestellungen
</f:facet>
<p:column style="width:16px">
<p:rowToggler/>
</p:column>
<p:column headerText="Bestellnummer">
<h:outputText value="#{order.id}"/>
</p:column>
<p:rowExpansion>
<p:dataTable id="exp" var="pos" value="#{order.orderPositions}" reflow="true">
<p:column headerText="Anzahl">
<h:outputText value="#{pos.quantity}"/>
</p:column>
</p:dataTable>
</p:rowExpansion>
</p:dataTable>
</h:form>

Answer 1

Solved it on my own: I adapted the rendered="#{orderModel.user.orders.size() > 0} to rendered="#{orderModel.userOrders.size() > 0} and added lazyLoading. Probbaly the first would be enough, but I think the accessed fields should be the same.