I also had an issue where my DNS needed to be pointed to the local MX. May not be your issue but support helped me troubleshoot that one. Otherwise as @WadeAlsup pointed out. HTTPS won't show the block message per https://documentation.meraki.com/MX-Z/Content_Filtering_and_Threat_Protection/Content_Filtering/Content_Filtering_Troubleshooting#Why_is_the_Meraki_block_page_not_displayed.3F
... View more