I would guess some of the issues with Colby's actor is the fact that he's a minor so he has a maximum amount of hours he's allowed to be on set, and he has to do school while on set as well (if I've understood U.S American filming laws correctly). Whilst the other actors don't have this restriction, so they've gotten to film a lot more. That being said, there's probably something else as well, as it's not normal for a minor to not be in episodes at all. Idk, that's just what I'm thinking
If that were the case he still would’ve been in episodes throughout, just spread out. Those labor laws are not new, and they don’t result in minors barely being in entertainment, otherwise Disney would very much be out of business.
Not being on screen at all for six episodes is definitely more of a „something came up so for now we’re doing this until he comes back“.














