Can't select checkbox in primefaces datatable using selection

I have a dataTable in primefaces and wish to select multiple rows, but the checkbox doesn't highlight when I hover over it and can't be selected when I click.

The checkbox is definitely enabled. Here is the code:

<p:dataTable id="deferDatatable2" 
            value="#{deferMaintenanceTasksBean.tasksList}"
            var="tasks"
            rowKey="tasks.jobId"
            selection="#{deferMaintenanceTasksBean.maintenanceTaskDatas}"                               
            styleClass="editable-datatable" >
            <p:ajax event="toggleSelect"
                listener="#{deferMaintenanceTasksBean.toggleSelect()}" />
            <p:ajax event="rowSelectCheckbox"
                update="deferDatatable2" />
            <p:ajax event="rowUnselectCheckbox"
                update="deferDatatable2" />
            <p:ajax event="rowSelect"
                update="deferDatatable2" />
            <p:ajax event="rowUnselect"
                update="deferDatatable2" />

             <p:column styleClass="select-column" 
                rendered="#{tasks.task.deferrable == 'true'}"                                   
                selectionMode="multiple" >  

            </p:column> 
            <p:column headerText="Task Code"
                 rendered="#{tasks.task.deferrable == 'true'}">
                <h:outputText value="#{tasks.task.taskCode}" />
            </p:column>
            <p:column headerText="Job Code"
                 rendered="#{tasks.task.deferrable == 'true'}">
                <h:outputText value="#{tasks.jobCode.code}" />
            </p:column>
            <p:column headerText="Description"
                 rendered="#{tasks.task.deferrable == 'true'}">
                <h:outputText value="#{tasks.task.description}" />
            </p:column>
            <p:column headerText="Safety Critical"
                 rendered="#{tasks.task.deferrable == 'true'}">
                <p:selectBooleanCheckbox value="#{tasks.task.safetyCritical}"
                    disabled="true" />
            </p:column>
            <p:column headerText="Deferrable?"
                 rendered="#{tasks.task.deferrable == 'true'}">
                <p:selectBooleanCheckbox value="#{tasks.task.deferrable}"
                    disabled="true" />
            </p:column>
            <p:column headerText="Att."
                 rendered="#{tasks.task.deferrable == 'true'}">
                <h:outputText id="i4AttachmentOutLbl"
                    value="#{tasks.task.attachmentCount}" />
            </p:column>
        </p:dataTable>

Inside the toggleSelect method there is just a log so I could see if the method is being called even though the checkboxes aren't being checked, but it isn't.

Like I say, the checkboxes all render as does everything else, and they aren't faded as if they were disabled, but they behave as if they were disabled. I have tried removing the styleClasses to see if they were somehow affecting things, but they aren't.

I have other working examples of this within my project and from what I can see I have set this dataTable up exactly the same, but for some reason it isn't working. The xhtml has the same ui:compposition and same outputStylesheets and outputScripts as these other pages and same basic layout, so I am convinced there is something I have missed from the dataTable, but no clue what.

Any suggestions appreciated.

Thanks