Did you play all five of his Step 3 Moments? There's one Moment "Hang" that has a Cove version and a Baxter version. If you do the Cove version you won't be able to play Baxter's Step 4 storyline.
To avoid Cove's version of Hang you need to say Baxter is coming to the beach with you at the start of Hang. If it's just you, Cove, Terri, and Miranda on the beach than you didn't get Baxter's version.
That's not how it works. Sorry for the confusion. When you're alone in your bedroom, the first thing you decide if it you're going to the beach with Cove, Terri, and Miranda or Cove, Terri, Miranda, and Baxter. You've gotta pick Baxter is coming too.