Not sure if it's helpful, but I had the same issue on xbox today.
I made a Cabin in multiplayer from my solo world, and had no issues until I decided to pop in a P2 to clear out the intro gift box. After doing that, I noticed that Pam wasn't showing up at the bus stop. I went to her trailer and she was back to her pre-bus villager schedule. I wondered if it was because certain events/cutscenes needed to "happen" for P2 to catch them up to where the overall save file was in progression (I went Community Center route). So, I took P2 through the intro motions (got the intro fishing rod, got the intro sword, elevator to 120, killed 10 slimes to get in the adventure guild) then I decided to test sleeping multiple nights with P2 logged in. I didn't get explicit cutscenes, nor did but after the second sleep with P2 logged in, I went to check if Pam was leaving her house at 8:30am as per her "bus repaired schedule" and behold - she was off to work again!
TL;DR - I think it's a matter of some possibly unclear progression overlap occurring in the background, where I can see many folks making the guest cabins, popping in a split screen and then subsequently encountering this.
(I'm curious if making yet another farmhand (P3?) would trigger the same issue - but I got some slight trauma from thinking I had a corrupt save. :3 )
I decided to chime in after panic searching google and this post popping up, being so recent. Hope this gives some insight!