Why is my websocket closing with code 1002?

I've been working with our 2nd Omnicore controller and unfortunately I am having trouble subscribing to resources via the Web API using a websocket connection. The websocket immediately closes with the following code:

"<info>closed Code: 1002 Reason: An exception has occurred while connecting."

This is confusing as we are using the same code and the same setup as with our 1st Omnicore system, where websockets are working ok.

The working system is running RobotControl 7.0.4 whereas the system we are having issues with was originally running 7.2.2, but I upgraded it to 7.3.0 in hopes of fixing the issue. However unfortunately it did not.

Below are the relevant REST interactions with the robot controller:

27/09/2021 13:47:00.089 PM : Session: 1 : POST : : resources=1&1=/rw/panel/ctrl-state&1-p=1 : Starting

27/09/2021 13:47:00.200 PM : Session: 1 : POST : : resources=1&1=/rw/panel/ctrl-state&1-p=1 : Complete

27/09/2021 13:47:00.200 PM : SUBSCRIPTION - Location: wss:// groupID: 11 : SUBSCRIPTION

27/09/2021 13:47:00.200 PM : SUBSCRIPTION - Cookies: -http-session-=24::http.session::11b801e5c15740036264713061ee4d76; path=/; domain=; secure; httponly,ABBCX=2228237; path=/; domain=; httponly : SUBSCRIPTION

27/09/2021 13:47:00.266 PM : Session: 1 : DELETE : :  : Starting

27/09/2021 13:47:00.271 PM : Session: 1 : DELETE : :  : Complete

For our C# code we are using virtually the same code as what is shown in the ElogSubscriber example provided by ABB. Though we have added this line in the WsConnect method:
"websocket.SslConfiguration.EnabledSslProtocols = SslProtocols.Tls12;"

Does anyone have any ideas as to what is going on here? If you need more information from me please just let me know.