Why is Spider Solitaire telling me there are no more moves available, when obviously there are?

Because you cannot progress. All you can do is move cards from one pile to another, but not to a position where you can make progress.

No, I was set to wipe off a whole stack (K – A) in just two moves (or 3 if I had shifted to the other red King,) which would have at least upped my score, even if I bombed after that. That is not the same as shuffling from one pile to another and going around in circles and not getting any points.

Granted, I don’t see any moves after that, but I thought the game was a bit premature in shutting it down when I still had 2 or 3 solid moves left and points to gain.

I suppose the game is programmed to know if you cannot fully complete the game. If you can’t, it shuts it down.

In the past it’s waited to shut you down when there were absolutely no moves left, not even useless ones like what @zenvelo described. This was just odd. I kept looking at it, thinking I was missing something, but if I am, I can’t figure out what it is.