UI Definition: Microsoft.Solutions.ArmApiControl UI element does not work

Hello Azure community,

I am encountering an issue with Azure Managed Applications regarding the use of Microsoft.Solutions.ArmApiControl in a Create UI Definition.

Background and Details:

• I have been using Microsoft.Solutions.ArmApiControl in my Create UI Definition file to retrieve dynamic data from the ARM API and populate dropdown controls, as demonstrated in the official documentation: https://learn.microsoft.com/en-us/azure/azure-resource-manager/managed-applications/microsoft-solutions-armapicontrol
• This approach was working as recently as a few months ago.
• Now, when I try to use this pattern in the Create UI Definition Sandbox (link), I receive the following error:

    Template deployment does not support ARM API and Graph API controls in UX configuration.
  

• A minimal example of my Create UI Definition follows (from the documentation):

{
  "$schema": "https://schema.management.azure.com/schemas/0.1.2-preview/CreateUIDefinition.MultiVm.json#",
  "handler": "Microsoft.Azure.CreateUIDef",
  "version": "0.1.2-preview",
  "parameters": {
    "basics": [
      {
        "name": "providersApi",
        "type": "Microsoft.Solutions.ArmApiControl",
        "request": {
          "method": "GET",
          "path": "[concat(subscription().id, '/providers/Microsoft.Network/expressRouteServiceProviders?api-version=2022-01-01')]"
        }
      },
      {
        "name": "providerDropDown",
        "type": "Microsoft.Common.DropDown",
        "label": "Provider",
        "toolTip": "The provider that offers the express route connection.",
        "constraints": {
          "allowedValues": "[map(basics('providersApi').value, (item) => parse(concat('{\"label\":\"', item.name, '\",\"value\":\"', item.name, '\"}')))]",
          "required": true
        },
        "visible": true
      }
    ],
    "steps": [],
    "outputs": {
      "providerName": "[basics('providerDropDown')]"
    }
  }
}

• The same template, and ARM API control specifically, used to work perfectly, but now always triggers the error above.

Questions and Request:

1. Has there been a recent change to the support for ARM API or Graph API controls in Create UI Definitions for managed applications?
2. If so, could you clarify if this is a temporary regression/bug or a long-term breaking change?
3. Is there any workaround or recommended approach for dynamically retrieving values (such as express route provider lists) in the current Create UI Definition system?
4. Can you please update the documentation if this feature is no longer supported, or if there are new requirements or limitations?

This feature is critical for the design of user-friendly managed applications, and clarification or a fix would be greatly appreciated.

Thank you very much for your help in advance.