How to unset Splunk cascading dropdown tokens in a proper way?

[deepikagooty]

I have a dashboard with cascading dropdowns which when a value selected in first dropdown populates the second dropdown with values based on the selection made.

For example the first dropdown has values A, B, and C. When A is selected from the first dropdown, the second dropdown should display A1, A2, and A3. Similarly should display B1, B2, B3 and C1, C2, C3 respectively.

My dashboard is populating the dropdown correctly. I am unsetting the second dropdown tokens when the first dropdown changes, to make sure the second dropdown do not contain previous token value. But this is causing me an issue while page reload. When the page is refreshed, the second dropdown token gets unset like shown below.

Before refresh

After refresh

If I do not unset the second dropdown tokens when the first dropdown changes, the second drop down shows the previous selected token as shown below.

My xml looks like this

<form>
  <label>Dependent Drilldown</label>
  <fieldset submitButton="false">
    <input type="dropdown" token="tokElement" searchWhenChanged="true">
      <label>Element</label>
      <choice value="A">A</choice>
      <choice value="B">B</choice>
      <choice value="C">C</choice>
      <change>
        <unset token="tokSubElement"></unset>
        <unset token="form.tokSubElement"></unset>
      </change>
    </input>
    <input type="dropdown" token="tokSubElement" searchWhenChanged="true">
      <label>Sub Element</label>
      <fieldForLabel>$tokElement$</fieldForLabel>
      <fieldForValue>$tokElement$</fieldForValue>
      <search>
        <query>| makeresults
| fields - _time
| eval A="A1,A2,A3",B="B1,B2,B3",C="C1,C2,C3" 
| fields $tokElement$
| makemv $tokElement$ delim=","
| mvexpand $tokElement$</query>
      </search>
    </input>
  </fieldset>
</form>

I would like my second dropdown tokens to be unset when first dropdown value changes and also maintain those tokens on page refresh. Let me know if you have any thoughts.