Steps to reproduce the issue

Add a multiple form field to an xml and load the field in a validate form view

XML Field like:
<field name="test" type="checkboxes" multiple="true" required="true"> <option value="test1">test1</option> <option value="test2">test2</option> </field>

Then try to submit and you see, that the client side form js validation did not work

Expected result

JS Feedback "required field" should be shown

Actual result

Nothing, form submits without any error

System information (as much as possible)

Joomla! 4.0.0-beta4 Beta [ Mañana ] 15-September-2020 13:46 GMT

Additional comments

Same problem on list field type