I see a trick they play on some, not all episodes. Some episodes, CW is only making it available for seven days and removes them from the on demand. So, if you want to watch them, you have to pay. They did this for the episodes I noted in my original post. I caught on by watching the day after an episode and saw that it was only going to be available for seven days. Other episodes were available for a longer period of time. Again, I think it is a way for you to have to pay and a revenue generator for the CW. For example. The 7/31, Damocles Part I is available only until TODAY 8/7. Yet the 7/24 episode, The Dark Year is available until 8/28. Every episode from S5 from 1 to 8 are no longer available. A total rip off.
Well, I was just coming here to update this (mine had no option to buy, it just said subscribe) and low and behold it's suddenly fixed. Only took TWO weeks of calling and "escalating" the issue. Maybe yours is back too!