UWP app throws exception saying the certificate has been revoked

[Rufus1123]

I have followed the Setup for the IoT part successfully and I have updated defaultRoomDevicesEndpoint and defaultRoomId in the AppSettings.cs accordingly. Now I am trying to go through this demo script: https://github.com/microsoft/SmartHotel360-IoT/tree/master/Documents/DemoScript

After I have logged in with the default credentials, it immediately gives me an error:

Error
An error occured, try again.

The exception occurs on line 35 of RequestService.cs for calls to "https://backend.smarthotel360.com:443"
var response = await httpClient.GetAsync(uri);
with message:

The text associated with this error code could not be found.

The supplied certificate has been revoked

I tried the following even though they are not part of the setup:
I have followed the steps https://docs.microsoft.com/en-us/windows/msix/package/create-certificate-package-signing to create the pfx file, and installed the certificate. I have also updated the csproj file with the thumbprint of the self signed certificate, but no luck.

I am not sure what's going on. I don't have a lot of experience with UWP apps, but I think I've set up the certificate correctly