I've noticed they only show up if you've selected at least one vagabond, in which case they are automatically randomly distributed among the ruins on the map. To see them you have to pick up the ruin tile to reveal the ruin item(s) underneath. I tested it with combinations of vagabonds and vagabots, and those all seem to work correctly as long as you select them before selecting the map.

The thing I noticed that doesn't work is that when the Tavern scenario is selected, no ruin items are generated. Since exploring ruins is one of the actions listed on the tavern board, I assume there should be ruin items there to find, even if there is no dedicated vagabond player.

We just started our first game of this mod. We see the Ruin tiles on the board and had to unlock them. Even when we did this, it appears that it is only a Ruin tile and nothing else.

Follow the setup instructions carefully - select the Vagabond fully before you load the map, and it works.