ADF: linkedService template function not defined - azure-data-factory

Question

I am currently trying to add some parameterised linked services. I have two services currently: a key vault, and a data lake. The configuration are:
// Key vault
{
"name": "Logical Key Vault",
"properties": {
"parameters": {
"environment": {
"type": "String"
}
},
"annotations": [],
"type": "AzureKeyVault",
"typeProperties": {
"baseUrl": "https://kv-#{linkedService().environment}.vault.azure.net"
}
}
}
// Data lake
{
"name": "Logical Data Lake",
"properties": {
"type": "AzureBlobFS",
"parameters": {
"environment": {
"type": "String"
}
},
"annotations": [],
"typeProperties": {
"url": "https://sa#{replace(linkedService().environment, '-', '')}.dfs.core.windows.net",
"accountKey": {
"type": "AzureKeyVaultSecret",
"secretName": "storageAccountKey",
"store": {
"referenceName": "Logical Key Vault",
"type": "LinkedServiceReference",
"parameters": {
"environment": {
"value": "#linkedService().environment",
"type": "Expression"
}
}
}
}
}
}
}
Both linked services are parameterised by an environment parameter, and I have confirmed that the Key Vault works fine and is able to correctly retrieve secrets. The problem happens when I attempt to retrieve the storage key from the key vault. I get the following error:
Error code
FailToResolveParametersInExploratoryController
Details
The parameters and expression cannot be resolved for schema operations.
Error Message: {
"message": "ErrorCode=InvalidTemplate, ErrorMessage=The template function 'linkedService' is not defined or not valid."
}
My attempts at debugging this has identified the use of #linkedService on line 38 to be the issue, which is when the Data Lake is trying to pass its own environment parameter to the Key Vault so that it may obtain the storage key. If I remove this use of #linkedService.environment and replace it with a hard coded value, the linked service successfully connects to the data lake.
The expression is trivially simple, and the web interface itself offers the option:
As a result, I am unsure why the use of #linkedService fails here. The web interface and ability to use expressions would suggest it should work, but then #linkedService is undefined for some reason.
While debugging this, I did find that using the expression
#string(linkedService.environment)
Does indeed work, but this seems rather odd as the environment is itself a string and thus its conversion into a string should be a no-op. I have also looked into removing the # entirely and trying
linkedService.environment
and while this does correctly resolve to the environment, it still results in an error as it resulting parameter contains the surrounding quotation and thus the linked service fails to connect to the key vault https://kv-'foobar'.vault.azure.net as it is clearly invalid (assuming my environment was foobar).