Had a chat with my local TK reps (RO call center, romanian speaking staff) and they have absolutely no idea as to why this is happening but they did confirm that they had several calls on this topic in the past few days.
If this is a system-wide bug of sorts (i.e. - 'regular' TK IT stuff) i'm really NOT looking forward to tens of pax shuffling around the J cabin and asking seatmates to switch with them or their travel partners.