Trying to mark messages with the read/unread or favorite icons in the mail list view results in IMAP errors, both on Kolab Now and my personal server running dovecot. Example errors:

Warning: {2876c209-6936-4a27-9592-a1608e3b8169}.imapserverproxy : Job failed: "Store failed, server replied: A000021 BAD Error in IMAP command UID STORE: Invalid arguments. " KIMAP2::StoreJob
Warning: {2876c209-6936-4a27-9592-a1608e3b8169}.imapresource : Error during changereplay: "Store failed, server replied: A000021 BAD Error in IMAP command UID STORE: Invalid arguments. "
Warning: {2876c209-6936-4a27-9592-a1608e3b8169}.synchronizer : Failed to replay change: "Store failed, server replied: A000021 BAD Error in IMAP command UID STORE: Invalid arguments. "
Warning: {2876c209-6936-4a27-9592-a1608e3b8169}.synchronizer.changereplay : Change replay failed: Error: 1 Msg: "Store failed, server replied: A000021 BAD Error in IMAP command UID STORE: Invalid arguments. " Last replayed revision: 29
Warning: {2876c209-6936-4a27-9592-a1608e3b8169}.synchronizer.changereplay : Error during change replay: Error: 1 Msg: "Store failed, server replied: A000021 BAD Error in IMAP command UID STORE: Invalid arguments. "
Warning: {2876c209-6936-4a27-9592-a1608e3b8169}.synchronizer : Changereplay failed: "Store failed, server replied: A000021 BAD Error in IMAP command UID STORE: Invalid arguments. "
Warning: {2876c209-6936-4a27-9592-a1608e3b8169}.synchronizer : Error during sync: Error: 1 Msg: "Store failed, server replied: A000021 BAD Error in IMAP command UID STORE: Invalid arguments. "
Log: {2876c209-6936-4a27-9592-a1608e3b8169}.synchronizer : All requests processed.
Log: kube.sinkfabric : Received notification: Notification(Type: "status" , Id: "changereplay" , Code: 1 , Message: "" , Entities: () )
Log: kube.sinkfabric : Received notification: Notification(Type: "error" , Id: "changereplay" , Code: 1 , Message: "Store failed, server replied: A000021 BAD Error in IMAP command UID STORE: Invalid arguments. " , Entities: () )
Log: kube.sinkfabric : Received message: "errorNotification" QMap(("message", QVariant(QString, "An unknown error occurred: Store failed, server replied: A000021 BAD Error in IMAP command UID STORE: Invalid arguments. "))("resource", QVariant(QString, "{2876c209-6936-4a27-9592-a1608e3b8169}"))("type", QVariant(int, 3)))
qml: Trying to show the notification An unknown error occurred: Store failed, server replied: A000021 BAD Error in IMAP command UID STORE: Invalid arguments.
Log: kube.sinkfabric : Received message: "notification" QMap(("message", QVariant(QString, "An unknown error occurred: Store failed, server replied: A000021 BAD Error in IMAP command UID STORE: Invalid arguments. "))("resource", QVariant(QString, "{2876c209-6936-4a27-9592-a1608e3b8169}"))("type", QVariant(int, 3)))