I am also struggling quite a bit with something very similar: We have an ambisonics renderer that requires 16 channels. Everything works fine using AVAudioFile to read a wav file with AVAudioChannelLayout.init(layoutTag: kAudioChannelLayoutTag_HOA_ACN_SN3D | 16) into AVAudioPCMBuffer I can't find any compressed formats that iOS is able to read at 16 channels. Whilst it seems possible to create an aac file with up-to 48 channels iOS doesn't seem able to decode anything with more than 8 channels (7.1) as far as I can tell? We considered using 2x8 channel aac files, reading them into 2 buffers and then joining them but have been unable to figure out how to merge them back to 16 channels with the correct layout. I'm currently experimenting with trying to use Opus for the compression but my experiments here have also been unsuccessful so far. Any help anyone can give on how we could go about getting 16 channels of compressed audio out of a file (or files) and into an AVAudioPCMBuffer with kAudioChannelLayoutTag_HOA_ACN_SN3D | 16 layout would be very amazing.

20 hours later and the errors magically stopped just as quickly as they started. Who knows? I'm just glad whatever it was seems to be at least partially resolved for us for now at least and I can finally get some sleep. zzz

As of May 3rd we have suddenly started seeing a lot of 21104 status codes in response to verifyReceipt calls (been like this for the last 20ish hours and still on-going) with no obvious reason why or pattern as to what receipts are causing it. Once a receipt hits this state it seems to be stuck with that code and no amount of retrying seems to help. No idea what is going on but it's causing us some serious issues.

We also found this this happened for the first time today. Exactly the same issue except our download_id was nil. Weird thing is that the bundle_id isn't just null but its the string "null" Also note: the receipt from the users device was correct but this issue was present in the unified receipt sent from the App Store INITIAL_BUY event callback. I am pretty certain it's a bug on Apple's end but nothing conclusive yet.