The ESXi was updated from 5.1 to 6.0.0 update 1. A new license is required. I took the license from the download site. Before I installed the license, I could power on or off any VM. After that, no power operations successful. After removing the license (the host is now again in evaluation mode) power operations working fine.
In both cases power control was possible by using Workstation. I didn't test it with the vSphere Client.
In which configuration detail you are interested ?