OK, I understand now.My post was describing Monday morning (19th) - your screenshot is from today's service (20th).
I have noticed that SWR can run a train between Woking and Portsmouth on the 24 Dec but not the 27 Dec. Both days are strike days for Network Rail. I assume the strike on the 2uth ends at 18:00 and that is why, as their staff not wanting to do overtime would mean it shouldn't be possible to run trains easily before they need to put them to bed, so to speak.