Thank you for contacting us and I'd be happy to assist.
This issue is already reported to the concerned team. If a post/page is part of a WPML access group, its preview only works for the 'administrator' role. Users with any other role, can’t preview it and see the 404 not found page.
I'm afraid, I don't have a time estimate for a fix, but, I'll keep you updated on the progress through this ticket.
Is there any specific reason for keeping the posts in the "Draft" status? If you're using this to track approved/unapproved status, you can use a workaround. You can allow the users to add posts in the "Published" and not "Draft" status and add a custom field "Approval Status", which can have two possible values "Approved" and "Unapproved". On the front-end, the display of these posts can be controlled using this custom field's value, instead of the post status.
I hope this helps and please let me know if you need any further assistance around this.