Looks like I have the same issue. When I create a custom field of type date, it shows up OK on the front end and you can select a date from the calendar but when you go to the cart neither the label ("arrival date") nor the date entered shows up. There's no label or date stored in the order in the admin and no label or date in the email. The data, however, is being stored in the virtuemart_order_items table in the product_attribute field. It would be great to get it working because the datepicker makes all the difference when it comes to different date formats being entered in a plain-text input.
Has anyone had any success using custom field of type:date on VM 3.0.16 or later?
This is on VirtueMart 3.0.18 running on Joomla! 3.6.5
Been at it too long... I'm now struggling to get the sum right in the wee captcha - lol
Soon be Christmas