we had the same issue...thanks to another post we managed to solve it!
The issue was related to a different way to collect the information in V8 than V7.
Now it seems the DNS configuration in ESXi plays a role... i got almost crazy, but once fixed the DNS in ESXi and rebooted everything is now working.
1) give a full host/domain name to the ESXi under configuration > DNS settings
2) make sure the DNS record exists in the DNS server used by ESXi and Veeam
The information given by the alarm should include that it might come from a DNS misconfiguration or missing record.