Most likely due to owners of the show. They have the most control on this.
Possibly a delay in getting all ways covered in sections under "On Demand" Check under Name of show or under Network since all links are entered at the same time. It might show up sooner under HD version than SD version.
Hello Pollyanna1952, the information that (MNtundraRET) shared is correct. It's up to the networks that own the content to post it on demand. Most new content is posted within 24/48 hours of the original air date, if the content is not there after 48 hours it is due to an error that occurred while posting the new show/movie. Please allow at least 48 hours for the newest episodes to be posted on demand.