I wanted to chime in yesterday but I didn't get a chance to. On your first attempt, I would sort of expect AP to function the way it did for you on that right lane near the exit ramp. As someone mentioned in another thread, the right dotted line disappears to signify the exit ramp and AP1 acted in the same fashion when it was initially rolled out. How does the AP system know where that lane marking went on the first pass? My steering also got a little erradic while driving in the right lane of a highway on Autosteer (I noticed it the first day I turned Autosteer on and immediately started avoiding lanes that transition markings like that), especially on the first day. I am now on day 4 and Autosteer is handing right lanes like a champ.
It was referenced that Tesla updates the cache on the maps (I believe) to account for this; perhaps it's happening on the fly. Before activating my TACC and AS after the update, I read through every page on the update notice. There were at least 5 places where these features were listed as beta. So far, my expectations of functionality align with my expectations of a beta are and I am not disappointed.