Try earlier versions? Or try CBR mode, maybe this will change the result.
Maybe related, or maybe not: https://hydrogenaud.io/index.php/topic,17773.0.htmlm4a container written by qaac is different from the ones created by iTunes. fb2k also writes some metadata which is never written by iTunes. Therefore, there *can* be a compatibility issue regarding container. MP4 is an unnecessarily versatile, complex format for storing a single audio track. Some kind of compatibility issues are quite common in poor parser implementations, especially seen in hardware players.However, since your ipod is able to play at least one track, I guess it's not simply because there's something in the container which iPod cannot handle properly.There might be an issue in the sync process when files came from outside of iTunes... but I really have no idea.
Support decoding FLAC in MP4. AAC decoder: now recognizes 6.1ch/7.1ch AAC channel config constants (11 and 12) defined in 14496-3:2009/Amd 4:2013 Concatenating files with no title tag with --concat now creates empty chapter name (formerly file name was used). --start now accept negative value. using --start and --delay at the same time is not allowed now. These two options are the same in functionality-wise, except for the reversed sign (For trimming, you use positive value for ---start, and negative value for --delay). --adts and --concat doesn't allow concatenating files with varying sample format anymore. External dlls are now loaded in lazy way, which means that they are not loaded until needed. Increased buffering size for --play to avoid glitches on multi channel files. --native-resampler now always use dedicated AudioConverter. CAF: enabled 7.1ch rear AAC output. AAC in CAF: when chan chunk is not present, get channel layout from kuki chunk. Named pipe output is removed. I guess it has been rarely used anyway, but if you happen to want it, use https://github.com/nu774/namedpipe .