Encoding problems using 7.1 Wav/W64 with HE-AAC

[Dendraspis]

Hello,

I have a problem encoding a 7.1 W64 file using AAC-HE, while AAC-LC works without issues.
I converted several W64 files before and had never issues with 5.1 and/or 2.0. AAC-LC works great with every configuration I've tested.

I used this command line:
qaac64.exe Test71.w64 -o Test71_QAAC_HE_v128.aac --he -v128 --verbose

Output:

Input layout: 7.1 (L R C LFE Ls Rs Lsd Rsd)
Format: int24 -> float32
Output layout: 7.1 (C L R Ls Rs Rls Rrs LFE)
AAC-HE Encoder, CVBR 128kbps, Quality 96
...

The result is an unplayable file. Apps tell me, that it is a stereo:
Audio: AAC 48000Hz stereo 132kbps [A: aac, 48000 Hz, 2 channels, 132 kb/s]

I also tried both versions - x64 and x86 with the same result.
After that I converted the resulting AAC file into a W64:

Input layout: 7.1 (C L R Ls Rs Rls Rrs LFE)
Format: float32 -> float32
Output layout: 7.1 (L R C LFE Ls Rs Lsd Rsd)
...

QAAC recognizes a 7.1 input, but the quality of the resulting W64 is awful, whereas converting an AAC-LC encode back to W64 sounds as intended.

Next step I tried this with an AAC-HE using -v256 :
qaac64 Test71_QAAC_HE_v256.aac --play
and it sounds terrible - noticable worse than AAC-LC at -v256.

So what's wrong? Is there a bug or am I something missing?

qaac64 --check:

qaac 2.68, CoreAudioToolbox 7.10.9.0
libsoxconvolver 0.1.0
libsoxr-0.1.3
libsndfile-1.0.28