Group messages silently dropped
Group messages can be silently dropped without indication. Once Whisperfish loses the sender key for a group (after mainly a transient missed SenderKeyDistributionMessage), it cannot decrypt further group messages and fails to notify the sender to re-share. Other clients recently stopped re-attempting SenderKeyDistributionMessage sends on transient failures, so this state no longer self-heals: affected groups will keep missing messages until the sender is triggered to re-share by other means. 1:1 messages are unaffected. A fix (implementing the DecryptionErrorMessage retry-receipt flow and sender-key re-share) is in progress.
References: whisperfish!793