Migrated/Imported Stacks do not update when stackset parameter is modified

[schwinbp]

Describe the bug
I migrated some our old AWS Landing Zone(ALZ) stacks to our new CfCT equivalent stacksets as part of our migration to Control Tower(ACT). Those stacks migrated successfully since the templates were exactly the same. Since then, whenever I update a parameter value in the ACT Manifest it shows that the StackSet parameter was updated. However, any stack instances in the that stackset that were imported from ALZ do NOT get updated. I have to manually go into the stackset, click Actions, Override Stackset Parameters and explicitly override the parameter that I want to update.

To Reproduce
1 - Setup CfCT for your ACT accounts.
2 - Import existing stacks(from ALZ) from a org child account into the CfCT StackSet int the management account.
3 - Migrate the ALZ account from previous stack into COntrol Tower.
4 - Updated a parameter in the ACT manifest to something different and run CodePipeline.
5 - See migrated account stack not updated.

Expected behavior
If you change a parameter value in manifest, and related stackset, ALL Stack instances should be updated with that value. YOu should have to manually override that stack parameter for each stack instance in Cloud Formation console.

Please complete the following information about the solution:

• Version: 2.7.0

To get the version of the solution, you can look at the description of the created CloudFormation stack. For example, "(SO0089) - customizations-for-aws-control-tower Solution. Version: v1.0.0". You can also find the version from releases

• Region: us-east-1
• Was the solution modified from the version published on this repository? No
• If the answer to the previous question was yes, are the changes available on GitHub?
• Have you checked your service quotas for the sevices this solution uses? Yes
• Were there any errors in the CloudWatch Logs? No

Screenshots
NA

Additional context
Add any other context about the problem here.