Block type cannot be used outside of array
Sanity Studio currently only supports using the block type in an array, not as a standalone field.
This will not work:
{
name: 'myField',
title: 'My field',
type: 'block'
}
But this will:
{
name: 'myField',
title: 'My field',
type: 'array',
of: [{type: 'block'}]
}