They don't have footage of the garage door opening, so I'm assuming its coming from the operator data. Assuming she had one installed in the last few years and it was hooked up to an app, they might be even able to tell how it was opened (force open manually, using someone's specific remote, keypad, etc). But they should have picked up it being disconnected if they were accessing this data the same way.
So they had to have known the door was opened a different time or the operator was disconnected, but don't take the car with them...? I'm just repeating myself again I realize but the more I sit on it the more baffled I get.
Edit: Of course, the car could have not been taken out of the garage. This is speculation under the assumption it was.