Test case:

• Set up in template discovery rule with item vfs.fs.discovery and filter with macro {#FSTYPE}

  and regexp "ext".

• Add single item to it like vfs.fs.size[ {#FSNAME},free],
  Observed behavior:
  * On next check in host which has this template linked appear generated items according to discovery rule, everything is fine.
  * On next check after generated items appear the item in discovery rule (vfs.fs.size[{#FSNAME}

  ,free]) becomes "Not supported". In agent's log I see "Active check [vfs.fs.size[

  {#FSNAME},used]] is not supported. Disabled." In server's log "item [hostname:vfs.fs.size[{#FSNAME}

  ,free]] became not supported: ZBX_NOTSUPPORTED"

If I remove filter from rule on host or template (doesn't matter), and reactivate item, the problem stops to occur.

I tried to check this on agent's side, but debug log doesn't reveal anything about this, so I guess it's server side problem.