Eggside octopus is unmissable.
If you want to try triggering it manually, it's "halloweenfour1". There's also a full log of the requirements at the wiki, you could check them one by one with URM to troubleshoot.
Although, if you have the guide mod and haven't tampered with the variables yourself through URM, I can hardly see what could have happened. Good uncle is a supported path in the game and will not cause your saves to fail. Maybe a bug while updating from an old build, that's my best guess.