RenderParam of type public is not storing value

I have the following link setup in a WCM component.
When a user clicks on the link, I'm trying to initialize a public render parameter to that the value stored inside citySelected is available to other components + multiple portlets.

[Plugin:ifNotEmpty value="[Plugin:RenderParam key='citySelected' type='public']"]
    Not empty.
[/Plugin:ifNotEmpty]

<a href="[Plugin:RenderURL 
    pr1.mode="set" 
    pr1.value="citySelected" 
    pr1.key="citySelected" 
    pr1.type="public" 
    title="">
        [AttributeResource attributeName="name" separator=","]
</a>

The problem is the value is not stored, but it is stored if I switch to a private parameter.
Currently when link is clicked the portlet is refreshed and tries to display the value, but nothing is ever displayed?

Need to pass a qualified name when setting a public render param e.g ..

[Plugin:RenderURL copyCurrentParams="true" uri="nm:oid:pageid" 
    pr2.key="{http://ibm.com}prp1" pr2.value="pv1" 
    pr2.type="public" pr2.mode="add"] 

http://www-01.ibm.com/support/knowledgecenter/SSHRKX_8.5.0/mp/social/plrf_rendr_plugin_render_url.dita