Having read over that adventure as an AL dm myself I am tempted to say it was an artifact of being a con-game . The one you ran was actually my favorite of the 5 mini-adventures because it does give you some pretty strong roleplay/combat opportunities, not much in the way of exploration in these mini-adventures. As a DM the description of the noble who gives you the mission I think makes for a potentially memorable character, and how you approach the patrons at the bar gives lots of leeway for both party and GM.

Another thing I have found is for any AL game, you can't really let people pursue everything they want. If I do let people rp every small thing, we lose up to an hour that could be spend with character or plot development. I treat my AL games like videogames with multiple paths. The party will get from point A to point B, but they way they choose to get there is entirely up to them, and their decisions will have real impact on what happens along this plot. Rather than open up every situation to the full array of possibilities, I tend to suggest courses of action based on what their characters are like. This keeps some of the pure durdling to a minimum and lets people get to combat/exploration/roleplay faster. If you want a game where literally anything is possible, AL might not be ideal. To fully enjoy the AL you have to buy in to whatever the current plot is and have fun within that.

I might be blessed with my current group, but 5/7 of them really embrace the roleplay, and I do my best to flesh out several characters. It's lead to a lot of good times over the last several months. The characters from lost mines will occasionally show up, and we still talk about few of the NPCs from the first season of expeditions. One expedition got two of our party members riled up because of how an interaction went with some NPC's. They were starting to ask the Crones too many questions about Elesendre and the party had grown attached to her in DEX 1-3

I think it's very possible to combine the three pillars in the adventurer's league. It's harder for a con-game, and it's easier when the DM knows what you like before hand. Not every DM will want to put that in their game, and not every dm is comfortable with that. I think you got unlucky and the DM you had wasn't feeling the same playstyle you were. I would encourage you to try it again, or even try DMing.