Rename segments to bigfile.000 , bigfile.001 , etc., strictly. Use cat to join them into a single raw image before ingesting.
The bigfile.000 file is often larger than 4GB. This creates a major problem because the older file system cannot handle files over 4GB. If your game is on a USB drive or an older external drive, this is likely the culprit. Unable To Open Bigfile Bigfile.000