query parameter not included in target

[kevin_kohut]

I am using an AssignMessage policy to add a query parameter to the request. The full configuration of the policy is below. When the flow gets to the target url, it does not add the query parameter. IN tracing the call, I see that the

target.basepath.with.query variable does not contain the query param.

I have confirmed that the {alexa.zip} variable exists and is correct.

Why isn't the query param being added to the target call?

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<AssignMessage async="false" continueOnError="false" enabled="true" name="AssignMessageSetQueryParam">
    <DisplayName>AssignMessage.SetQueryParam</DisplayName>
    <Properties/>
    <Set>
        <Verb>GET</Verb>
        <QueryParams>
            <QueryParam name="zip">{alexa.zip}</QueryParam>
        </QueryParams>
    </Set>
    <IgnoreUnresolvedVariables>true</IgnoreUnresolvedVariables>
    <AssignTo createNew="true" transport="http" type="request">request</AssignTo>
</AssignMessage>