The isssue is the "file recording mode," and it may be set for Stereo, Mono, or 6-channel, and the manual states pretty clearly that the 6CH setting will give you one 6-channel file, so while that may not be what you'd like to have, it shouldn't be too surprising that's what it is. Easy enough to just use mono or stereo to work with four channels, but maybe not quite as convenient.