If I also change the name for the server (proxmoxnode in the url) to my server's correct name, it gives me the correct response:
{"data":{"type":"ata","attributes":[{"name":"Raw_Read_Error_Rate","fail":"-","flags":"POSR--","value":79,"id":"...
it responds with {"data":null}
running any smartctl commands against the drives from the cli works just fine however.
edit. here is some more info from the request:
:8006/api2/json/nodes/proxmoxnode/disks/smart?disk=/dev/sda:1 GET...
I'm experiencing the same thing.
Based on what the Web Dev Tools say in Chrome, Javascript is getting a TypeError for property setVisible from the proxmoxlib.js