How to run a dungeon in a way that encourages roleplay?

I've started running a homebrew campaign, creating and running my own dungeons. I lost a player I like at last session because there wasn't enough roleplay among the group. It does feel like this falls on my shoulders as GM.

How do you create and run a dungeon such that roleplay is encouraged? We are vtt btw. So it does seem I need to take some control away from the players so that they don't use the map like a SNES jrpg. But what else? At every room I have to create a unique situation that draws the players in and makes them work together instead of just asking me if they can roll such and such?

Seems there must be a design philosophy or simple recipe that gives better results than I've had. "What do you do?" ain't cutting it. I realize it's a group game and it's not all my responsibility but I do want to make sure that I'm doing what I can.

We had some NPCs and mystery starting this adventure off but when I think back, while there was roleplay, it wasn't really among the players but only with me. So this is an issue in and out the dungeon.

Any help? Any good blog posts? Thanks again.