Does the same issue appeared if you disabled the plugin? If it does, then the issue is specifically caused by the plugin and for your information, Blog Posts plugin is a third-party plugin which is not developed by Atlassian therefore our knowledge on this plugin would be limited. I'd suggest you to directly contact the author of the plugin to get further assistance on the issue at:
Do you use templates with Confluence? Take part in a remote 1-hr workshop. You'll receive USD $100 for your time! We're looking for people to participate in a remote 1-hr workshop...
Connect with like-minded Atlassian users at free events near you!Find a group
Connect with like-minded Atlassian users at free events near you!
Unfortunately there are no AUG chapters near you at the moment.Start an AUG
You're one step closer to meeting fellow Atlassian users at your local meet up. Learn more about AUGs