I recently installed a plugin for site health checking and it has been showing me this error for a couple weeks now, and I was not sure why until I contacted Hostgator support and they were able to check the cause of the issue on the server. They said that it was Bluishost causing this error and wanted to ask you guys for a fix or some help with this please.
Your site could not complete a loopback request – Performance issue
This error can highlight a problem with scheduled tasks on your site. WordPress scheduled tasks are automatically run at set time intervals. You might find that scheduled posts don’t post, or backups don’t take place when expected.
Loopback requests are requests from your web server back to itself. These trigger the WP-Cron task scheduling system which automates the tasks.
Some hosts (notably Heart Internet) block loopback requests by default.
Troubleshooting this error can be tricky. You may need your host’s help.
I found for a site that I run with this error that setting the ALTERNATE_WP_CRON constant to true allowed my scheduled tasks to run.
However, it did not stop Site Health showing the error. I’m still investigating why, but I’m not worrying about it too much.