Zabbix Agent Interface greyed

[mururoa]

Hello,
I have a strange problem with some of my monitored hosts.
The Zabbix agent icon near the host is greyed. This is the icons under availability when I'm at Configuration / Hosts ZBX|SNMP|JMX|IPMI.
When all is ok it's green. When there is a communication problem it's red. But some are just greyed, like unused.
I looked on errors on logs but I found none relevant.
So I tried to remove the host and add it again with no luck : same result.
For example, a host has only one template : Template OS Linux. Basic data from the template are received by the server like CPU or OS or Memory metrics.
The only error I can see is in Latest Data on the item Disk Space on /var
vfs.file.size[file] there is an error message : "Cannot obtain file information: [2] No such file or directory". But there IS a /var on the server.
It look like the discoveries fail somewhere and that prevent the server to be marked OK.
There is only the basic graphs. The 3 CPU, memory, swap. Any of the filesystem or network graphs created after successfull discovery are available.
Where to look to find what fails ?

Edit : On the server the data is correct :
zabbix_agentd -t vfs.fs.size[/var,pfree]
vfs.fs.size[/var,pfree] [d|88.616101]

[batchenr]

Hello,
I have a strange problem with some of my monitored hosts.
The Zabbix agent icon near the host is greyed. This is the icons under availability when I'm at Configuration / Hosts ZBX|SNMP|JMX|IPMI.
When all is ok it's green. When there is a communication problem it's red. But some are just greyed, like unused.
I looked on errors on logs but I found none relevant.
So I tried to remove the host and add it again with no luck : same result.
For example, a host has only one template : Template OS Linux. Basic data from the template are received by the server like CPU or OS or Memory metrics.
The only error I can see is in Latest Data on the item Disk Space on /var
vfs.file.size[file] there is an error message : "Cannot obtain file information: [2] No such file or directory". But there IS a /var on the server.
It look like the discoveries fail somewhere and that prevent the server to be marked OK.
There is only the basic graphs. The 3 CPU, memory, swap. Any of the filesystem or network graphs created after successfull discovery are available.
Where to look to find what fails ?

Edit : On the server the data is correct :
zabbix_agentd -t vfs.fs.size[/var,pfree]
vfs.fs.size[/var,pfree] [d|88.616101]

snmo has issues when some of the items connected to the host is "Unsupported", if you see such items disable then.

now which zabbix version you use ?
when this happens what do you see at zabbix server log ?