I already ran the 1mb capture through my same C# code, and the 1mb file was well distributed, so it doesn’t seem to be my code there.
If there’s another environment to test in, without setting up a full VM with a unix distro, I’d be happy to run some other tests.
I don’t know if using USB 3.0 ports or 2.0 port would make a difference, but I’ll check some other ports.