Strange behavior in creating page where there is a TextArray field

Expected behavior

Actual/Current behavior

Steps to reproduce the actual/current behavior

1. create a model like this:

const Test = new keystone.List('Test');

Test.add({
	tags: { type: Types.TextArray, required: false, initial: true },
	remark: { type: String, initial: true },
});

2.visit admin ui and open create page(ie. [http://localhost:3000/keystone/tests]), click 'Create Test' 3.Then click 'Cancel' button but the popup window does not close.And all other fields seems to be disabled until you add some tags. 4.If some tags are added first, then the page works normally.

Environment

Software	Version
Keystone	4.0.0-beta.5
Node	6.10.1