The events tab in the vSphere Client shows a small number of events. The possibility of this issue has increased after the introduction of vSphere Cluster Services (vCLS) virtual machines in 7.x. Events related to these objects are restricted for many users, which causes misinterpretation of the events data by the vSphere Client. As a result, this causes the events page to not fully load and the navigation button to grey out.
VMware vCenter Server 8.0.2
VMware vCenter Server 7.0.x
This issue has been fixed in vCenter Server 8.0 U2 and 7.0 U3q.
A possible workaround is to try logging in with an Administrator account.
Note: This may still not work for some customers.