What mystery? ST seems to have cleared anything up. Or is this more about you being "right"?
Well, since my setting in my Windows 7 system is still at the default 5 hours for Check images, the issue didn't seem to cleared up yet. If that were the issue, then changing that setting to be a shorter time should resolved it but ST has tried that and apparently that setting change did not resolve the issue.
But, I agree ST seems to have the best clue so far to what may be going on here:
Now it's even worse. A huge picture of our friend the cassette player, cropped at the top, against a listing for a "Kitchen lot". It certainly seems that the cache is implicated somehow, if my dicking around with the settings provoked this...