This is sadly not a bug. It is a result of player reward pack cards, unfortunately, only being released into the client in foil.
This thread here is a request to change that, and hopefully if they do change it they can slowly work backwards and release previous month's new cards in nonfoil when we have months that don't require new cards to be added.
Yeah, at this point there are more players on Mtgo who prefer non-foil versions of cards to foil ones, and so it’s bizarre that these would only be released in foil.