title: Unsupported item key in Zabbix discovery
body: <p>I am using zabbix 4.0.
  Trying to make discovery with simple check.
  When i click "check now", i get Unsupported item key warning. Below you can find my discovery configuration. I couldnt solve why does it give this error. Everything seems fine.</p>
  
  <p><a href="https://i.stack.imgur.com/X8oYC.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/X8oYC.png" alt="enter image description here"></a></p>