Actors credited as "Self" not in full cast list

I notice that two actors that are credited as appearing "as Himself" in episode listings do not have that episode included on the full cast / crew list for the programme. They are: James Casey (VI) and Eli Woods who both appear in "Last of The Summer Wine" series 27 episode Plenty of Room in the Back However this episode is missing from their entries in the Full Cast and Crew for the programme. Is this normal or a glitch? If it is "normal", why ...? If it is a problem, how can it be rectified?