I ran into this problem with a fresh install of ESXi 6.5u1. This is a known issue with the specific version of the embedded client. Version 1.21 is the broken one; we need 1.24 or later.
Here is how to fix it in 3 steps:
- Download the vib file from here
- Upload to root of datastore
- Connect SSH, type esxcli software vib install -v /vmfs/volumes/yourvoulemeID/esxui-signed-7119706.vb