Steps to reproduce:

1. Create eg a graph to an item on a dashboard to a host with eg. a Visible name of Zabbix server
2. Change the Visible name of the host to Zabbix server to Zabbix server newname  the previous item

Result:

The Dashboard item will looose it's the connection to the host, and show an empty item

Expected:

The item should show the item, because the host itself is the same. Just the Visible name was changed

I think this issue is pretty much in all versions.