SetAudioMonitorType Action Returns Error Invalid Request Type

[vulgerrity]

I set a button to change a source's audio monitor to "monitorOnly." When I push the button my my MIDI device, the console reports, "[2020-10-21 22:08:00,312] (ERROR) T15644 : OBS returned error: invalid request type"

Here's my config:

"1": {
            "msg_channel": 0,
            "msg_type": "note_on",
            "msgNoC": 32,
            "msgVoV": 127,
            "input_type": "button",
            "action": "{\"request-type\": \"SetAudioMonitorType\", \"message-id\" : \"1\",\"sourceName\" : \"L1_Spotify\", \"monitorType\": \"monitorOnly\"}",
            "deviceID": 1,
            "bidirectional": false
        },

[vulgerrity]

I receive the error both with a "note on" and a "Control Change."

[vulgerrity]

Disregard...my websocket was somehow out of date.