When registering the Custom Post Type, ensure custom-fields is present in supports => array('editor','title', 'custom-fields')
. It’s the legacy wording of meta fields and is commonly mistakenly omitted when declaring supports in CPTs.
After you make the above change, your Team CPT should work with meta values. You still may encounter in Gutenberg initially, the meta values are ‘undefined’ as they don’t have a default value set. A default value can be set either when registering the Post Meta eg. 'default' => 'test string'
or in the block attributes.
NB. The documentation has been updated since this question was posted ref: trac #47866
Refer to the latest WordPress REST API to see all the changes