I checked on my dev cluster and can confirm that " in channels "{}" appears every time a document was deleted by CBL 2.x on Android. Here’s a code snippet of the Android client:
database.delete(document);
As some documents refuse to sync but others do sync I think my issue is similar to one of my past issue which was already solved. Here’s the solution. Grepping the sg logs I didn’t find similar logs as I saw in my other forum post. I’ll keep digging!