It is good to see you post about this issue here. But this problem seems to be one that comes up regularly here. There are a lot of complaints about tickets getting revoked/suspended/flagged after transferring Amex miles to Flying Blue. Even if there's no official rule against it, perhaps there might be an issue with the fraud system mistakenly flagging legit users? Since you have taken note of the problem, maybe you can encourage some sort of a review internally.

Of course, it is wholly possible that perhaps those people complaining here aren't telling the whole truth.

Either way, always good to see you pay attention to issues personally.