dim minnow
I just updated my game with the new hotfix and I noticed that lily is missing on the island and when I try too use the find npc function it tells me that this person is not around.
At first lily's map icon was showing but it was nina that was there not lily then nina disappeared and it started showing the same for her when I tried to look for her with the find npc function.
I just noticed it, not sure if it's a problem but wanted to bring it up.
south vessel
I have noticed that for several NPC and I can say that It's normal I believe It's their schedule to not be not be on island 24/7
obtuse fossil
In year 1, Nina only shows up in Summer, and winter I think (may have to wait till Spring Year 2), for Lily that's a new one, just restarted a new save and haven't had that issue. But like Duck said, some characters are not around 24x7 and do leave the island but come back in a few days. Antonio for example, and there's a few others.
solar lagoon
I know sometimes Lily goes to Nina's place. If she's there while Nina is not, you can't get into the house. I wonder if that's what's happening here.