Is there an existing issue for this?

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Current Behavior

When do you try to update using the command update-thing-groups-for-thing it gives an error ResourceNotFoundException

Expected Behavior

It should work. According to the documentation, it's implemented.

How are you starting LocalStack?

With the localstack script

Steps To Reproduce

How are you starting localstack (e.g., bin/localstack command, arguments, or docker-compose.yml)

localstack start

Client commands (e.g., AWS SDK code snippet, or sequence of "awslocal" commands)

REGION=us-east-1
THING_NAME=bob
awslocal iot create-thing --thing-name "$THING_NAME" --region "$REGION"
awslocal iot create-thing-group --thing-group-name "A:group1" --region "$REGION"
awslocal iot create-thing-group --thing-group-name "group2" --region "$REGION"
awslocal iot add-thing-to-thing-group --thing-name "$THING_NAME" --thing-group-name "group2" --region "$REGION"

Failing call:

awslocal iot update-thing-groups-for-thing
--thing-name "$THING_NAME"
--thing-groups-to-add "A:group1"
--thing-groups-to-remove "group2"
--region "$REGION"

Environment

- OS: Windows 11
- LocalStack:
  LocalStack version:  4.10.1.dev1
  LocalStack Docker image sha: 
  LocalStack build date: 2025-10-31
  LocalStack build git hash: e1972609c

Anything else?

No response