Azure.ResourceManager.Resources.SubscriptionResources.GetResourceGroups() returning empty

For the code below, it is getting the search service if using Microsoft.Azure.Management.Search. It is not getting the resource group if using Azure.ResourceManager.Resources.

public static async Task<string> GetAdminKeysAsync(IAzureCredentialFactory credentialFactory, string subscriptionId, string serviceName, bool useAzureResourceManagerForAdminKeys)
    {
        if (!useAzureResourceManagerForAdminKeys)
        {
            var accessToken = credentialFactory.AcquireToken(Common.SystemConstants.Security.AzureManagementEndpoint);
            SearchManagementClient searchManagementClient = new SearchManagementClient(new TokenCredentials(accessToken))
            {
                SubscriptionId = subscriptionId
            };
			// Service found (see below code GetResourceGroupNameFromServiceName)
            string serviceResourceGroupName = GetResourceGroupNameFromServiceName(searchManagementClient, serviceName);
            var adminKeys = searchManagementClient.AdminKeys.Get(serviceResourceGroupName, serviceName);
            return adminKeys.PrimaryKey;
        }
        else
        {
            var tokenCredential = credentialFactory.AcquireTokenCredential(Common.SystemConstants.Security.AzureManagementEndpoint);
            var armClient = new ArmClient(tokenCredential, subscriptionId);
            var subscription = await armClient.GetDefaultSubscriptionAsync();
			// ResourceGroup not found
            var resourceGroups = subscription.GetResourceGroups();
            foreach (var resourceGroup in resourceGroups)
            {
                var searchServices = resourceGroup.GetSearchServices();
                foreach (var searchService in searchServices)
                {
                    if (searchService.Data.Name.Equals(serviceName))
                    {
                        var adminKeys = await searchService.GetAdminKeyAsync();
                        return adminKeys.Value.PrimaryKey;
                    }
                }
            }
            throw new InvalidOperationException($"Service name {serviceName} can't be found from subscription {subscriptionId}.");
        }
    }
	
	public static string GetResourceGroupNameFromServiceName(SearchManagementClient searchManagementClient, string serviceName)
    {
		// Service found
        IPage<SearchService> searchCollection = searchManagementClient.Services.ListBySubscription();
        SearchService searchService = searchCollection.SingleOrDefault(azs => azs.Name.Equals(serviceName));
        string searchId = searchService.Id;
        Match matches = ResourceGroupIdPattern.Match(searchId);
        if (matches.Groups.Count < 2)
        {
            throw new ArgumentException($"Could not find resource group name in {searchId}.");
        }
        return matches.Groups[1].Value;
    }

Please try by changing the following line of code:

foreach (var resourceGroup in resourceGroups)

to

await foreach (var resourceGroup in resourceGroups.GetAllAsync())