"Apply" not being enabled in Dataflow Pipeline run configuration

[chanseokoh]

The test plan says

Run > Run Configurations.... Select the configuration you created earlier, and select the Pipeline Arguments tab.

Select DataflowRunner. Wait for a second, and verify Pipeline Options change to list many more options.

Uncheck Use Default Dataflow options. This should enable all the fields under the checkbox. (FYI, all the fields under the checkbox are supposed to be disabled when the checkbox is ticked, but due to a bug, you might see some of them are enabled beforehand.)

Select an account and a project ID.

Enter <a unique, non-existing bucket name to create>/subfolder in the staging location. You'll see an error message "Cloud not fetch bucket ...". Verify Create Bucket is enabled.

Click Create Bucket. The dialog should show a message that the bucket is created.

Click Apply and then Run.

However, the "Apply" button is kept disabled. Changing the GCS staging location or the project ID doesn't enable it either. Interestingly switching to other tabs enables "Apply" (along with "Revert").

Changing the staging location (typing some characters) and clicking "Close" loses the change. Normally, it should pop up a dialog asking for saving or discarding any changes.