That is certainly strange to see. You should be able to see all the episodes if you can watch one of them, as that wouldn't make much sense! I will be honest, I would like to get back to you on this one as I'll need to run a quick test. In the meantime, can you please let me know if you can tell me what package TV size you're on?
Off the top of my head I'm not 100% which package we're currently on. It's one of the smaller ones, M+ or More - we don't have Sky 1 HD so it makes sense that we wouldn't be able to watch the HD version.
Before the tivo update / menu redesign we used to filter the on demand content by package size, so we only saw what we could access. Since the update I can't tell whether or not this is still possible, so when we access on demand we see everything, even content that is not included in our package. We now have to manually select things in order to check if we can watch them or not. I don't know if this is relevant or not, but is it still possible to only show the content available to each package?
Thanks for getting back to me on this one, I've been looking into this and if you've got the M+, if the content resides in channels that you do no subscribe to now, this would be the reason why you cannot see them.
My apologies for the late reply and hope that this has shed some light