Heh, yep this is still on the list, and earlier I did confirm where it's coming from--exactly the cause you mention, those unfinished rooms.
You're correct in that those rooms are generated but only marked to be dug out, though in the case of hidden doors the excavation team actually doesn't know how to accommodate those. Technically it was an oversight when I wrote the excavation event--I didn't realize there might be unfinished hidden passages attached to the target area.
So my solution could have been to simply retroactively remove the secret passage itself, or let them know how to connect the two (but the latter requires more code and testing...).
If this is still on remove list please consider removing it from it. I mean it, the list - not the game. Duh, that was clumsy.
Hahaha. I've marked down your vote to keep it
It's cool that you managed to figure it out, by the way, and saw what was happening there. I imagine most are going to just continue reporting this as a bug (more than one player has mentioned it now...), which is one of the reasons I was going to remove it. Or maybe I'll teach them how to do it. Anyway, not super high priority right now.