They may have uncovered something that wasn't in their scope or are just trying to pass the buck onto the next person.

when i recently made the big move from nyc to signal hill, ca, i could not get a mortgage cuz i write and wrote off most of my taxable income to uncovered medical costs (was blinded in both eyes couple yrs back while doing humanitarian work overseas, but can now see again after multiple surgeries), and relocation expenses for the past 2 years.so, i purchased at around market value with half a million in cash savings. it really depleted me, and by the time i'm done with rehab, will be BROKE!

So, the Due Diligence fee should be no more than the amount your are comfortable losing if property inspections uncover something that would be considered a deal breaker for you.

If you find a deal that appears to offer 20% cash on cash(with or without financing, or whatever,) then you're missing something- like the roof will need replacing very soon, the likely tenant base is untenable, the house is hot with lead paint/asbestos, your sewer line was plumbed through your neighbor's basement because 50 years ago the neighbor's were super chummy and wanted to save some dough, but now the fancy lady who just bought the adjacent house has uncovered this fact and guess what!

Financial due diligence helps in making informed investment decisions by providing key performance indicators (KPIs) such as financial position, operational performance, and liquidity. These KPIs provide critical insi...

If so, they could be doing this to protect you from uncovered Workers Comp claims (a former client got sued by handyman for workers comp. 

They might fix some or all of the punch list items uncovered and then have the report updated to reflect those repairs.

This will likely only effect a small percentage of landlord/investors that specialise in S8.

Seriously though, all this thread will do is uncover the snitches

Juts like apples you some times have to uncover the rottenness.