Is there a specific time at which it always happens or, is it random? That might help to pinpoint what it could be.

Barring anything corporeal, I'd get some sage smudge sticks/incense and smudge the whole place, along with doing a ritual "leavetaking" for whomever/whatever might be hanging about.

Oh, and your mystery writing was fine...I got the under-the-floor grabbing just didn't think there'd be much point in answering as you been "got" and presumably would be unable to return!**bg**