Cannot get params over to rewrite url properly in Azure Api Management - azure-api-management

Question

I'm trying to make apim take rewrite...
https://apimpath/customers/1234
to
https://backendpath/api/customers/1234
It fails. Tried a few things but they all don't seem to recognize customerId. What am i missing?
------Update-------
Tried some of the suggestions below and it didn't help. Here is the new ui showing the same message
Tried adding it through the api with several variations of this...
PUT {{url}}/apis/customers/operations/GET?api-version=2016-7-7
{
"name": "GET",
"method": "GET",
"urlTemplate": "/{customerId}",
"templateParameters": [
{"name": "customerId", "type": "string"}
],
"policies": null
}
Which added the operation successfully...
PUT {{url}}/apis/customers/operations/GET/policy/?api-version=2016-7-7
<policies>
<inbound>
<base/>
<rewrite-uri template="/api/customers/{customerId}"/>
</inbound>
<outbound>
<base/>
</outbound>
</policies>
But the request above failed with this result...
{
"error": {
"code": "ValidationError",
"message": "One or more fields contain incorrect values:",
"details": [
{
"code": "ValidationError",
"target": "rewrite-uri",
"message": "Error in element 'rewrite-uri' on line 4, column 10: Only parameters specified in the original URL template can be used in the rewrite template. Original template is: /*"
}
]
}
}

Answer 1

This seems to be a bug. I can recreate this as well.
If you create the operation with a parameter, this is saved somewhere.
Changing it doesn't seem to work, because
The correct order is to create the operation directly with the right parameter name. Then add the backend rewrite rule.
If you take a look at the screenshot, the original operation you created was "/*" and not "/{customerId}"
I tested this in the new UI/Portal.
I created an operation "/{id}",
Added the rewrite "/api/{id}"
Tested it and it worked
renamed the operation to "/{customerId}"
encountered below error:
One or more fields contain incorrect values:
Error in element 'rewrite-uri' on line 16, column 10: Only parameters specified in the original URL template can be used in the rewrite template. Original template is: /{id}