Synthetics visual reference not respecting cloudformation template update

I deployed an AWS synthetics canary with visual reference (the screenshot comparison) through cloudformation. It worked for a while until I need to update the baseline visual reference. I noticed that updating the cloudformation template does NOT actually update the visual reference config in canary. I verified through checking CFN template and then use AWS CLI to check the canary's config. I believe this is a bug.

Then I tried to use AWS CLI to update the BaseCanaryRunId in visual reference config. The update did work but the visual comparison stopped after it. Seems like there is a massive bug around the update of a AWS synthetic canary.

Is my diagnosis correct or am I missing some steps here.