[Bug] [Templating] [dot Net] `$when` condition doesn't work as expected with `$index` and `$data`

Platform

What platform is your issue or question related to? (Delete other platforms).

• .NET 5.0

Author or host

Are you an author (like sending something to Outlook), or a host that is rendering your own cards? If host, please specify the corresponding host (app) name.

• Author

If you're an author, who are you sending cards to?

• Microsoft Teams

Version of SDK

What version are you using? Ex: NuGet 1.0.2, or latest main, etc...

• Dot Net NuGet AdaptiveCards.Templating 1.2.2

Issue

When I call AdaptiveCardTemplate.Expand() to bind data to an AdaptiveCardTemplate, the returned card is missing some elements whose $when condition should be evaluated as True.

In the meantime, the online designer expands that card correctly.

Repro Steps

Code

var cardTemplate = new AdaptiveCardTemplate(templateJsonString);
string expand = cardTemplate.Expand(dataJsonString);
Console.WriteLine($"Contain TextBox: {expand.Contains("Index 1")}");

Sample Template

{
	"$schema": "http://adaptivecards.io/schemas/adaptive-card.json",
	"type": "AdaptiveCard",
	"version": "1.3",
	"body": [{
		"type": "Container",
		"$when": "${$index>0}",
		"items": [{
			"type": "TextBlock",
			"text": "Index ${$index}"
		}],
		"$data": "${foo}"
	}]
}

Sample Data

{
	"foo": [1, 1]
}

Expanded Card String

{"$schema":"http://adaptivecards.io/schemas/adaptive-card.json","type":"AdaptiveCard","version":"1.3","body":[]}

Expected behavior

The expanded card should contain a TextBlock, whose text is Index 1. Just as the online designer does.

{"$schema":"http://adaptivecards.io/schemas/adaptive-card.json","type":"AdaptiveCard","version":"1.3","body":[{"type":"Container","items":[{"type":"TextBlock","text":"Index 1"}]}]}

Start at AdaptiveCardTemplate.Expand() and reproduce the issue with the provided C# code, template, and data. Compare the .NET expansion with the online designer, focusing on how $when is evaluated alongside $index and $data. Done means the expanded card includes the Container and TextBlock with "Index 1" as shown in the expected JSON.