Sorry Cannot give the address of that site as it is my private development site, however on my live site I am only getting this one (but critical) issue:
Your Site could not complete a loopback request
Loopback requests are used to run scheduled events, and are also used by the built-in editors for themes and plugins to verify code stability.
The loopback request to your site failed, this means features relying on them are not currently working as expected.
Error encountered: (0) cURL error 28: Operation timed out after 10000 milliseconds with 0 bytes received
This I can troubleshoot to the plugin email before download
HOWEVER:
I just rechecked the development site (which is a clone of the live site and on the same server) and it has two issues
The one above plus
The Rest API has encountered an issue. Even with Email before download disabled.(Actually disabled, not just in Healthcheck)
However trouble shooting on that site is not possible as it seems the enabling and disabling of plugins is faulty:
When bulk-disabling plugins, a site failure occurred. Because of this the change was automatically reverted.
When disabling the plugin, rss-includes-pages-pro, a site failure occurred. Because of this the change was automatically reverted.