I am also currently upgrading from 2.x to 3.0 and I was able to confirm that if a document is removed from a channel where the user does not have access to, the document is indeed auto purged even with version 2.8 of Couchbase lite.
However this worked when the mutation was executed from Couchbase dashboard, when I try the same mutation from Couchbase lite SDK ( which will update the document and run the sync function logic to change the channel assignment), the document is not auto-purged. In both cases I was able to validate that the user and document channel assignment are as expected.
Do we need to be on Couchbase lite 3.0 to handle both cases I described above ?
Thanks
Adrian