Add line item properties to dynamic checkout button "Buy it now"

I try to add line-item properties to dynamic checkout button “Buy it now”.


 
 
 Label

It sends properties only when i click on “Add to cart” and then on the cart page click on “Check out” button.
I need properties to be sent from the product page when i’m clicking on “Buy it now” button. In this case now i receive

"properties": null,

Does anyone can help to solve this issue?
Thanks.

Have you ever solved this issue?