<single>
<search>
<query>|query</query>
<earliest>$time_token2.earliest$</earliest>
<latest>$time_token2.latest$</latest>
</search>
<option name="drilldown">all</option>
<option name="refresh.display">progressbar</option>
<drilldown>
<set token="hide_details">$click.name$</set>
<unset token="form.hide_details"></unset>
</single>
<input type="checkbox" token="hide_details">
<label></label>
<choice value="hide">Hide Details</choice>
<change>
<condition value="hide">
<unset token="hide_details"></unset>
</condition>
</change>
<delimiter> </delimiter>
</input>
</drilldown>
You have included both set and unset in the drill down and that might be the reason.
Assuming that you have another detailed panel which is visible only when you click on the single value panel, try below run anywhere example
<form>
<label>test</label>
<fieldset submitButton="false">
<input type="time" token="time_token2">
<label></label>
<default>
<earliest>-15m</earliest>
<latest>now</latest>
</default>
</input>
</fieldset>
<row>
<panel>
<input type="checkbox" token="hide_details">
<label></label>
<choice value="hide">Hide Details</choice>
<change>
<condition value="hide">
<unset token="hide_details"></unset>
</condition>
</change>
<delimiter> </delimiter>
</input>
<single>
<search>
<query>index=_internal|stats count</query>
<earliest>$time_token2.earliest$</earliest>
<latest>$time_token2.latest$</latest>
</search>
<option name="drilldown">all</option>
<option name="refresh.display">progressbar</option>
<drilldown>
<set token="form.hide_details">true</set>
</drilldown>
</single>
</panel>
</row>
<row>
<panel depends="$hide_details$">
<table>
<search>
<query>index=_internal|stats count by sourcetype</query>
<earliest>$time_token2.earliest$</earliest>
<latest>$time_token2.latest$</latest>
</search>
<option name="drilldown">none</option>
<option name="refresh.display">progressbar</option>
</table>
</panel>
</row>
</form>
You have included both set and unset in the drill down and that might be the reason.
Assuming that you have another detailed panel which is visible only when you click on the single value panel, try below run anywhere example
<form>
<label>test</label>
<fieldset submitButton="false">
<input type="time" token="time_token2">
<label></label>
<default>
<earliest>-15m</earliest>
<latest>now</latest>
</default>
</input>
</fieldset>
<row>
<panel>
<input type="checkbox" token="hide_details">
<label></label>
<choice value="hide">Hide Details</choice>
<change>
<condition value="hide">
<unset token="hide_details"></unset>
</condition>
</change>
<delimiter> </delimiter>
</input>
<single>
<search>
<query>index=_internal|stats count</query>
<earliest>$time_token2.earliest$</earliest>
<latest>$time_token2.latest$</latest>
</search>
<option name="drilldown">all</option>
<option name="refresh.display">progressbar</option>
<drilldown>
<set token="form.hide_details">true</set>
</drilldown>
</single>
</panel>
</row>
<row>
<panel depends="$hide_details$">
<table>
<search>
<query>index=_internal|stats count by sourcetype</query>
<earliest>$time_token2.earliest$</earliest>
<latest>$time_token2.latest$</latest>
</search>
<option name="drilldown">none</option>
<option name="refresh.display">progressbar</option>
</table>
</panel>
</row>
</form>