Cache not getting cleared in Front page

Hi Team,

I am trying to clear the cache programmatically using cron job. I am using the following code to clear the cache.


But the problem is, the front page is still getting me the cached value. Its not clearing the cache. The other pages are fine with the latest values updated.Can anyone give me the solution. I am using the drupal version 8.2.x.

Drupal version: