Manafort doesn’t appear to be an idiot. If he had/has any business records at his residence by the time the Gestapo raided his house - with all the warning signs that they were coming - then he is by definition an idiot.
First thought was that there is something they want he keeps on his person... Investigation-related or not.
Goods on someone else perhaps.
We lost this place several decades back... Somewhere around 1000 points of light.
Manafort had literally months to anticipate the raid. It would not surprise me if he planted hundreds of fake leads and documents which are simply red-herrings. Mueller could be wasting two years on documentation that he eventually discovers to be ‘fake’.
Actually one would expect Manafort’s house to be brimming with notes as he was preparing testimony for the Senate Intel Committee that very morning. This was a case of the Special Counsel interfering with a congressional investigation.