Ok, so I checked, these episodes are in the History as "Cancelled". I can set them up to record individually, but there seam to be no way to get them to record again as a series.
I note when I try, it asks "Record as Set"? What baloney, as it's not set to record! And if I select this, it shows the multiple record icon in the guide on it, but it shows no intention to record any of the other shows in the series.
I think you have hit this bug on the head Earl.... I think it's totally confused because I cancelled the recording on these shows once, now it will never allow series record on these again!
Another bug. The prioritizer and history are are really badly settup. There is no way to understand this History thing.