No embedded audio except first 16 channels on 8K decklink

When trying to output more than 16 channels of audio using the the 8K decklink pro card, I cannot find any audio expect for 1 SDI output.

The device is configure as a single subdevice using all 4 ports, and I am sending a 8K60 video at the same time. I tried both to configure the number of audio channels with 32 and 64, but both lead to the same result.

The API calls seem to all succeed without error:
hr = m_piDeckLinkOutput->EnableAudioOutput(bmdAudioSampleRate48kHz, bmdAudioSampleType32bitInteger, iNumChannels, bmdAudioOutputStreamContinuous);
hr = m_piDeckLinkOutput->ScheduleAudioSamples(ptr, blockSize, 0, 0, &samplesWritten);

I made sure that ptr contains valid data for all channels.

It seems to have been caused by an incompatibility with AJA 12G cards (perhaps others as well). Between 2 Decklink cards there were no audio issues.

With Kona5/Corvid44 12G the 64 channels are split over the 4 SDI outputs with 16 channels each, while with the Decklink 8K pro all channels are multiplexed within the first 12G SDI output.
The approach used in Decklink is according to the ST2084-12 standard.