Mailwizz API and Subscriber Form Multiselect

When I use the iframe or the auto created form the multiselect works fine. When I use my own form and use the API I get the following error. Can I modify the API/Mailwizz to accept a multiselect via API or is it not possible?

"The field SUBSCRIPTIONS contains multiple values, which is not supported right now!"

The array I am submitting is

                'digital'    => 'digital',
                'newsletter' => 'newsletter',
@Mike Oltmans - The error comes from /apps/api/controllers/List_subscribersController.php Line 355
You could remove the " && !is_string($value)" condition and see if that works.