Unable to make use of derived type properties

[Dash]

Bicep version
0.30.23 (ec3612e)

Describe the bug
I am trying to make use of the functionality added in PR #13047, but it doesn't seem to work and I get:

Error BCP391: Type member access is only supported on a reference to a named type. [https://aka.ms/bicep/core-diagnostics#BCP391]

To Reproduce
Steps to reproduce the behavior:

1. Create a new bicep file following the syntax described, e.g.

param baseName string = resourceGroup().name
param location string = resourceGroup().location
param name string = '${baseName}-nsg'

param securityRules resource<'Microsoft.Network/networkSecurityGroups@2023-09-01'>.properties.securityRules

resource nsg 'Microsoft.Network/networkSecurityGroups@2023-09-01' = {
  name: name
  location: location
  properties: {
    securityRules: securityRules
  }
}

2. Run az bicep build -f myfile.bicep
3. Witness the errors:

testy.bicep(5,21) : Error BCP391: Type member access is only supported on a reference to a named type. [https://aka.ms/bicep/core-diagnostics#BCP391]
testy.bicep(11,20) : Error BCP062: The referenced declaration with name "securityRules" is not valid. [https://aka.ms/bicep/core-diagnostics#BCP062]

Additional context
Visual Studio Code extension also doesn't like this syntax.

[jeskew]

@Dash Resource-derived types are an experimental feature and need to be explicitly enabled. Try adding a bicepconfig.json file in the same directory that looks like this:

{
    "experimentalFeaturesEnabled": {
        "resourceDerivedTypes": true
    }
}