Naoto-Ida/storybook-6.3-defaultvalue-reproduction

A repro of the default value not being selected in the Controls column.

Steps

Run

cd sb-regression 
yarn storybook

Open http://localhost:6006/?path=/docs/example-button--primary&globals=measureEnabled:false

Problem

After upgrading from 6.2.9 to 6.3.0, we've lost the feature to have SB select the default value in the Controls column.

For example, in the demo files produced with npx sb init, a Button.tsx is created. Its size prop has a default value of medium, but the RadioControl does not select the radio option labeled medium anymore.