I'm having the same quest progress issues too. Samantha keeps asking me to visit her house more often, but I’ve already shared it with Ken and the quest still won’t complete. I’m also stuck on Gabriel’s quest and Charlotte’s quest. Even though the story has moved forward, there’s no update in my quest log at all. Plus, it seems that getting stuck on Charlotte’s Monday quest is stopping me from accepting the quests for both Charlotte and Phoenix.
Like I said earlier, as long as you can still play the game and complete the quests until the end even though some of those quests are still not considered complete in the Journal, it's okay. It's an already known bug since earlier versions of the game.
As for Samantha keeps asking you to visit her house even after you already shared her with Ken, it is her repeatable dialogue.
As for Gabriel, as long as you already completed his requests until you had a threesome with him and his wife, then his quest is complete.
As for Charlotte, I don't know how you got stuck with her quest so I'll list the step by step below:
- You picked Anna Route when Charlotte asked you about something between you and Anna
- You already have Anna on 5 Hearts and on Slut Route.
- You have a threesome with Anna and Charlotte on the Yacht on Monday
- You visit the Yacht again until you get to pick between Titjob or Anal with Charlotte
- Visit the Mall and you find Charlotte being harassed with a random guy.
- Go to the Gym the next day and persuade Phoenix to be Charlotte's bodyguard ( Make sure you already completed Phoenix's Quest first until the end )
- Go to the Entrance of your Home on Thursday and you'll introduce Charlotte and Phoenix to each other
- Go to the Mall the next day and you'll see Phoenix doing her job well. There is an extra scene of them in the Boutique ( RNG )
- Go to the Yacht on Monday and you'll get an extra scene with Phoenix and Charlotte. That is it for Charlotte's Quest.