Amazon Lex V2 NextStep Issue

The issue you're facing is likely due to a limitation in AWS CloudFormation when defining NextStep or CaptureNextStep properties for an Amazon Lex V2 bot. Currently, CloudFormation does not support directly referencing the target step or intent within the same template.

To work around this limitation, you can create a separate CloudFormation resource for the target step or intent, and then reference its ARN (Amazon Resource Name) in the NextStep or CaptureNextStep property.

Here's an example of how you could define the NextStep in your CloudFormation template:

1. Create a separate resource for the target intent:

MyTargetIntent:
  Type: AWS::LexV2Bot::Intent
  Properties:
    BotId: !Ref MyLexBot
    IntentName: MyTargetIntent
    # Define your target intent properties here

2. In your MainMenuIntent, reference the ARN of the MyTargetIntent resource in the NextStep:

MainMenuIntent:
  Type: AWS::LexV2Bot::Intent
  Properties:
    BotId: !Ref MyLexBot
    IntentName: MainMenuIntent
    Description: Provides the caller an option to give another input
    InitialResponseSetting:
      InitialResponse:
        MessageGroupsList:
          - Message:
              PlainTextMessage:
                Value: Sure, Please tell us the reason for your call.
      NextStep:
        DialogAction:
          Type: Intent
          IntentQualifier: !GetAtt MyTargetIntent.IntentSignature

Replace MyTargetIntent with the appropriate resource name for your target intent, and MyLexBot with the resource name of your Lex bot.

Note that this approach may require some restructuring of your CloudFormation template, but it should resolve the issue you're facing with the NextStep definition.