Deckbox Sellers section not showing any sellers anymore

Since yesterday or so, the Deckbox Sellers section of card pages does not show any sellers anymore, and seems to be related to location. It defaults to "Shipping to Canada",  and when I either click on "Show All Deckbox Sellers" or select "Show All Sellers" in the combobox, then it correctly shows available sellers. Browsing to a different card page resets the selection. I also know that the "Shipping to Canada" option is not working properly, as some sellers do ship to Canada, but the list is always empty.

Thanks!