I have a screen set up to show graphs of my Zabbix DB nodes, Zabbix Server nodes and Zabbix Proxies.

If you change the Group to something other than 'all', say 'group1'..and select a host from that group, say 'host1' some of the elements on the screen disappear as they do not belong to that group / host.

If I then change the group from 'group1' back to 'all', I cannot set the value of Host to 'not selected'.

What you can do, is reselect the group, say 'group1', set the value of Host back to 'not selected', then change the group back to 'all which will bring the filter back to normal.

It would be nice to be able to reset, or default those filters or have the ability to set Host to none/not selected.