After installing Veeam One , login to Veeam One Business View worked , however Veeam One Reporter with the same login details came back with 

The specified username or password is not correct. Provide new credentials and try again.

After Checking the C:\Program Files\Common Files\Veeam\Veeam ONE Settings\VeeamOneSettings.exe and what the service was started as these where all correct.

I was using firefox to login , so I tried with Internet Explorer with the same details and it worked straight away!

***Update if this still doesn’t work

Log onto the server where Veeam ONE is installed.

Open Local Users and groups, ensure that the user in question is added only to the Veeam ONE administrators group.

Log off then log back on and attempt opening the monitor console.