For AAC files with APEv2 tags the length calculation was off, since the size of the APEv2 block was used in the estimate. Now the length of the APEv2 block gets taken out of the length estimate.
Only some software supports APEv2 tags in AAC files, for some software it even causes issues with length calculation or playback. Let the user configure whether to save APEv2 to AAC, not save APEv2 to AAC or completely remove APEv2 from AAC.