When mass editing clubs some don't appear after filtering

Initially I mass edited each club filtered by division from the premier league to vanarama national north and south however the next season when using the same filter that I had previously it would only find 18 clubs. I believe this is due to relegations and promotions but it makes mass editing these teams then impossible. For instance if you filter the division to Sky Bet Championship you should get 24 clubs in your search results however I only get 18 and each season this becomes less and less. If you need screenshots just ask and I can show what I mean if I havens been clear enough.