I recently installed Server 2016 from volume license. Everything went normally on the install. However, when going to activate, I’d click on Change product key and nothing would happen. Nothing.
However, launching the same activation GUI from the CMD line worked just fine.
slui 3
I can’t find a lot of documentation on this issue, so it would appear to be a fluke. There is also the option to enter the key directly from CMD line.
slmgr.vbs /ipk {key}