Chris J Davis
Overtext pending moderation...
The monster was the "Riot" that spawns outside the hotel. The unrevealed tile was the storefront to the east of the hotel and the investigator was standing in the space just east of that unrevealed tile. Since the Riot was around, we didn't want to explore around the storefront so we simply didn't reveal it. The Riot was supposed to move but it would have to go through the hotel and out the back in order to get to the investigators when it in reality could just move east through the storefront tile.
In the end we moved it through the unrevealed tile since the riot would've seen that investigator in reality. It felt cheap to let it go into the burning hotel.
The Riot moves differently to other monsters. If t should move onto an unrevealed tile, then it should be removed from the board until such time as it comes back to a revealed tile (and all of this should be instructed to you on the app).
This sounds like a potential bug, so might be worth reporting to FFG.